Platelet sensitivity to antiaggregatory prostaglandins (PGI2, PGE1, PGD2) was studied in 143 patients (122 male) with angiographically proven peripheral vascular disease and compared with age-matched clinically normal controls. Patients had a significantly lower platelet sensitivity to PGI2, PGE1, and PGD2 than controls. Clinical stages had no significant influence on the platelet sensitivity to PGI2 and PGE1. Patients with stage IIa had a lower sensitivity to PGD2 than patients with stage IV, the difference not being significant. Analyzing the influence of risk factors like diabetes, hyperlipoproteinemia, or smoking, there seemed to be an inverse relation between risk factors and platelet sensitivity to PGI2 and PGE1. Smokers especially, together with smokers exhibiting an additional risk factor, exhibited the highest prostaglandin consumption (PGI2, PGE1) and therefore the lowest platelet sensitivity. However, it has to be emphasized that the differences were not significant. There was a significant correlation between platelet sensitivity to PGI2 and PGE1, whereas this was not the case between the respective sensitivities to PGI2 and PGD2. This supports the hypothesis that both these prostaglandins (PGI2, PGE1) share the same receptor on the platelet surface, whereas PGD2 has its own receptor.