A high risk of venous thromboembolism or an increased bleeding tendency has been reported in patients with clinically diagnosed or occult cancer. That is why, in this study, the presence of platelet dysfunction in patients with newly diagnosed Hodgkin's disease was investigated. Platelet aggregation studies were performed in 31 patients with a mean age of 27.53+/-2.75 years and in 31 healthy volunteers with a mean age of 24.37+/-3.21 years. None of the patients had a history or a finding of bleeding diathesis or thromboembolism. A Lumi-Dual platelet aggregometer (Chrono-Log Corporation, Model 450) was used for platelet aggregation in platelet-rich plasma. Platelet aggregation responses were evaluated with ADP, collagen, epinephrine, and ristocetin. No significant difference could be found when compared with the results of healthy volunteers. In five of the patients, a primary, but not a secondary, response to ADP (2 microg/ml) was obtained (p < 0.02). Platelet dysfunction was not found in patients with newly diagnosed Hodgkin's disease in this study. One of the various pathogenic mechanisms of tumour-related thrombosis or haemorrhagic diathesis may play a role in oncological patients; for this reason, each patient should be investigated individually.