Alf Nachemson was one of the giants of his generation in the now recognised and developing specialty of orthopaedic spinal surgery. He spent a year or more in the USA, involved in editorial work and research, particularly at Boston, and remained a popular figure at American spinal conferences, where he drove home his strong views. Despite this, he remained scathing of what he considered to be the American tendency of resorting to surgery prematurely in situations where the outcome was still in question, citing particularly spinal fusion. Born on 1 June 1931, Alf Nachemson graduated in medicine from the Karolinska Institute in Stockholm, Sweden, in 1956 and, after his internships, studied for his PhD at Uppsala University. He then joined the staff of the Sahlgrenska Hospital, Göteborg, in 1961. Here he was appointed orthopaedic specialist and associate professor. He was promoted to professor and chairman of orthopaedic surgery at Göteborg University in 1971 and remained in this position until his retirement in 1996. He built up the research faculty of his department and developed a large research budget. His major involvement was in basic science research and clinical trials related to spinal orthopaedics. When he was first at Uppsala University, under the direction of Carl Hirsch, he became involved in the in-vitro and then in-vivo studies on lumbar disc mechanics. Initially this work involved intra-discal pressure measurements on post mortem specimens, but he developed his techniques to provide a safe method of measuring in-vivo intra-discal pressures in the lumbar spines of volunteers in different postures of flexion, extension and whilst lifting. This classic study, published in the *Journal of Bone and Joint Surgery* in 1964, and since corroborated in other centres, has become the scientific basis of our understanding of what is and what is not the correct use of the back in sitting, bending, lifting and carrying, according to the avoidance of disruptive internal disc pressures. From the late 1960s onwards, he set up a number of controlled prospective trials and random studies into the results of different spinal surgical procedures, correlating these with the outcomes of conservative treatment for the management of back pain arising in the workplace and in industry. Perhaps the main conclusions, which he derived from these controlled studies, was that bed rest for acute low back pain should be limited to no more than a few days and that lumbosacral fusion was rarely a useful treatment for chronic back pain, except where there is a clear mechanical cause, for example in cases of spondylolisthesis. He travelled the world and banged the table with this message (often literally), particularly in the USA, where there is a much higher prevalence of spinal fusion compared with Europe. Nachemson also made significant contributions to the field of spinal deformities and published on the poor longevity of severe infantile scoliosis, as well as the prevalence and pattern of back pain in different types of adult scoliosis. In the late 1980s he initiated an international multi-centre prospective control study into the effects of bracing in adolescent idiopathic scoliosis funded by the Scoliosis Research Society of the USA. This extended over some five years and its eventual publication concluded that bracing made a significant difference to the natural history of mild cases. Although the trial was at that time unique in its ambitious attempt to coordinate a study across several continents, unfortunately it did not extend the follow-up time long enough to answer the question as to whether bracing significantly altered the likelihood of a braced adolescent with scoliosis avoiding the need for eventual surgical correction. Alf Nachemson published over 500 scientific papers as first author or co-author and gave more than 1,500 lectures worldwide. Not only did he publish in Swedish and international journals, but was the co-founder of the journal Spine and remained their senior editor for 20 years. He was also one of the founders of the Cochrane Collaboration Back Review Group, established in 1993, which promoted a more scientific approach and the need for a higher standard of papers published in the spinal specialty journals. Among his many initiatives, he helped to found the European Spinal Deformities Society and the European Spine Society. Nachemson was appointed an honorary fellow of our College in 1987 and an honorary fellow of the British Orthopaedic Association the following year. In the last decade he had taken up the baton of promoting evidence based medicine, using this as a yardstick against which he felt that all treatments and methods of management must be judged. Undoubtedly his drive in this area has helped to make evidence based medicine not only a priority in spinal management, but also an everyday medical term. It could be said that Alf Nachemson’s greatest contribution was the establishment of a very successful university department of orthopaedics at Göteborg. Among his postgraduate students, 81 PhD theses were successfully defended, and 16 of his PhD students became notable professors in centres around the world. His department attracted many grants and achieved many awards. He worked in close collaboration with the Volvo car company based in Göteborg, which promoted research into back pain. There is good evidence that his team designed the anthropometrics for Volvo car seats. As with most distinguished medical Swedes, his English was impeccable and in addition he was an anglophile. As a result he enjoyed his frequent visits to friends and colleagues in the UK. These included not only to those in his own spinal specialty, but to general orthopaedic surgeons, of whom one stands out. Alf always enjoyed a good debate in the controversial areas of orthopaedics and it was Michael Freeman of the London Hospital who often provided this intellectual stimulus for him. Overall, Alf Nachemson was indeed highly gifted; not only as a lateral thinker with a research mind, but also as a good clinician, and one able to communicate with the patient over the options of treatment and their likely outcomes. One thing he despised was the ‘trigger happy’ surgeon. More than that, he was a charismatic team leader providing inspiration for a generation of spinal surgeons, not only in Sweden but worldwide and in this direction his energies were seemingly limitless. In one extended itinerary as a visiting professor he visited 50 universities in Australia, New Zealand, Asia, South Africa, North and South America and Europe. Outside medicine his interests largely revolved around his close family circle. He died on 4 December 2006 and is survived by his wife Ann and his children Louise, Mikael, Lotta, Sophie and their families.