A number of fluorenyl and diphenylmethane analogues of verapamil, chosen as having the same substituents arranged in different ways around the quaternary carbon, were synthesized in order to evaluate the importance of the stereoisomerism at that point of the molecule. The compounds were tested with the Langendorff technique and coronary perfusion pressure (CPP), left ventricular pressure (LVP), and heart rate (HR) were recorded. While most of the compounds were almost inactive on these parameters, three of them did show interesting cardiovascular action. In particular they produced a more pronounced decrease in CPP than verapamil, with a less marked negative inotropic effect. Structure-activity relationships and the mechanism of action of the compounds are discussed.