Different platelet preparation techniques have not previously been compared directly and simultaneously with respect to in vivo platelet viability. Using a dual-label technique with 111-In and 114m-In, platelet apheresis was compared with the platelet-rich plasma (PRP) procedure with respect to platelet recovery and survival (n=4). Furthermore, a continuous flow cell separator (Cobe 2997) and an intermittent apheresis system (Haemonetics V50) were compared with each other (n=4). No differences in platelet viability were found between the PRP-platelets and the apheresis-platelets. Also no differences were found between the two apheresis systems. Although different platelet preparation methods result in a varying degree of platelet activation, no difference in platelet viability has been observed.