Platelet changes in thalassemia included prolongation of bleeding time (30%), thrombocytosis (29%), decreased platelet retention (79%), and normal PF3 release. Platelet aggregation was found to be hyperaggregation in 50%, normal in 22%, and hypoaggregation in 28% of the studied patients. Platelet changes in thalassemia can be hyper-, normal, or hypofunction. The changes are likely to be related to many factors, particularly to the progress of the disease. Platelet hypoaggregation may lead to a bleeding problem. Platelet hyperaggregation and thrombocytosis were prominent in the splenectomized patients and/or the severely anemic group; antiplatelet drugs may be indicated in these patients.