The literature on the spontaneous regression of cancer is reviewed from 1966 to 1987 to update reviews by Everson & Cole and by Boyd. These authors reviewed all cases of spontaneous regression from 1900 to 1965. We then report the entire series from 1900 to 1987. We also attempted to determine what attributions for spontaneous regressions have been reported. Although almost half of the authors failed to speculate or specify a possible cause for the spontaneous regression, the remainder postulated responsible factors such as immunological or endocrine, surgical, necrosis, infection, or operative trauma. The only unorthodox treatment to appear in the literature was the psychological. We conclude that the literature on the spontaneous regression of cancer is still unable to provide unambiguous accounts of the mechanisms operating to affect these regressions.