Platelets play a role in the development and complications of coronary artery disease (CAD) and a number of abnormalities of platelet function which can be corrected by antiplatelet drugs have been described. Betathromboglobulin (BTG), a platelet-specific protein which is released from α-granules during platelet activation is significantly elevated in patients with angiographically demonstrated CAD (51.0 ± 31.0 ng/ml., n = 50) compared to normal (28.0 ± 8.0 ng/ml., n = 70) p < 0.001. The effect of sulphinpyrazone (800 mg.) or aspirin (1200 mg.)/dipyridamole (200 mg.) on plasma BTG in CAD was studied in a blind prospective crossover trial in 25 patients. Mean BTG concentration pre-treatment was 52.3 ng/ml. and after 1 month’s treatment with placebo, sulphinpyrazone or aspirin/dipyridamole mean plasma BTG concentrations were 53.5, 49.6 and 56.7 ng/ml. respectively. Analysis of variance showed no significant difference between the means (p > 0.1) . This study confirms increased plasma BTG concentrations in patients with CAD and indicates that therapeutic doses of these antiplatelet drugs do not significantly effect the BTG level and thus appear not to prevent α-granule release in CAD.