'Sol' Penn was born in Rokiskis, Lithuania, on 15 January 1930. His family emigrated to Johannesburg, where he attended Athlone High School and studied medicine at the University of Witwatersrand in Johannesburg. He completed a series of junior posts at the Baragwanath Hospital. He then went to England for postgraduate training in surgery. Having passed his FRCS, he then went to North America to study under Charles Rob in Rochester, Colin Ferguson in Manitoba and F A Simeone in Cleveland. In 1966 he did a residency at Strong Memorial Hospital at the University of Rochester, and was chief resident at the University of New York, Syracuse, before moving to Colorado to work under Tom Starzl in the field of transplantation. There he was made chief of surgery in the Veterans Administration Hospital, before moving on to Cincinnati Veterans Administration Hospital in 1982. There he was recognised as an outstanding teacher, receiving many awards from his peers and his students. He was much in demand as a visiting professor, in which role he made more than 440 visits all over the globe. He was secretary and vice-president of the International Transplantation Society, and received many awards from professional societies. His many publications reflected an unusually wide range of interests, chief of which was the incidence and consequence of malignant tumours in transplant recipients receiving immunosuppressive medication, of which one of the most common was lymphoma. By a cruel irony it was a B-cell lymphoma that led to his death. In 1954 he married Zelda, by whom he had two children, Michelle and Jonathan. He died on 18 November 1999.