Clinical and experimental data suggest that ergotamine compounds and triptans may contribute to vascular events such as myocardial infarction and stroke. The role of blood cell aggregation in this context is, however, not clarified. We aimed to evaluate the impact of different acute antimigraine compounds on platelet and erythrocyte aggregation in a human ex vivo experimental design. In 20 healthy subjects without migraine and in 20 healthy subjects with migraine without aura, platelet and erythrocyte aggregation were measured before and after intake of placebo, acetylsalicylic acid, ergotamine tartrate, zolmitriptan and sumatriptan. Platelet aggregation was measured by the so-called platelet reactivity index. Erythrocyte aggregation was measured by photometric assessment in an aggregometer. Ergotamine tartrate induced a significant increase of platelet aggregation, whereas acetylsalicylic acid induced a significant decrease in both subject groups. After placebo, after sumatriptan and after zolmitriptan, no significant changes of platelet aggregation were noted. Erythrocyte aggregation was affected by neither compound. We can conclude that platelet aggregation, but not erythrocyte aggregation, is increased after intake of ergotamine tartrate. This may in part contribute to vascular side-effects of this compound. Acetylsalicylic acid and the triptans appeared to be safe with respect to platelet and erythrocyte aggregation.