The influence of chronic verapamil treatment on the development of human coronary sclerosis was retrospectively investigated in 26 patients; 17 nontreated patients served as controls. The same issue has been dealt with prospectively in a second and still ongoing, double-blind, placebo-controlled study in 444 patients selected after bypass surgery. The retrospective study on patients treated with verapamil revealed a slower development of the overall coronary disease with a slower progression in individual stenoses, more pronounced regression, especially with high-grade stenoses, and less frequent occurrence of new significant stenoses. The question is still open as to whether these effects can be confirmed by the prospective study, the data of which will be available at the end of January 1991, at the earliest, on completion of a 3-year follow-up.