OBJECTIVE To investigate the circumstances surrounding why Egas Moniz was not awarded the Nobel Prize for his contribution of angiography, provide a synopsis of Moniz's political and medical careers, and present a biographical sketch of Hans Christian Jacobaeus, the neurologist who evaluated Moniz's Nobel Prize nominations, as well as to dispel long-standing misconceptions concerning Moniz's recognition and to acknowledge the contributions of other researchers. BACKGROUND In 1936, António Caetano de Abreu Freire Egas Moniz published the results of a radical treatment for mental illness, a surgical procedure he termed prefrontal leucotomy. Moniz achieved such remarkable results with mental patients who suffered from conditions previously deemed incurable that many physicians throughout the world immediately embraced the procedure. In 1949, the Nobel Prize Committee recognized Moniz's contribution with the Nobel Prize in Physiology and Medicine. Why Moniz's earlier major contribution to medicine, the discovery and development of angiography, was not acknowledged in like fashion has remained a mystery. Nobel Prize documents reveal that Moniz was nominated for the award on two separate occasions; both times, Jacobaeus, Chairman of the Department of Neurology at Karolinska Institute and a member of the Nobel Prize Committee, evaluated the nominations and recommended against awarding Moniz the prize. CONCLUSIONS The development of imaging techniques was not isolated to any one individual's contribution. Several persons, including Walter Dandy and Jacobaeus, were leading figures.