In this paper we report on studies of platelet adhesion to several fibrinogen gamma chain variants under physiological flow conditions. Reduced platelet adhesion was found to patient dysfibrinogen Vlissingen and its recombinant form (deletion of gamma 319-320). Furthermore, substitutions of the amino acids 318, 320, or both in the recombinant fibrinogen gamma chain showed a strong decrease in platelet adhesion under flow conditions in our perfusion system. Antibodies raised against peptides covering these sequences inhibited platelet adhesion completely, which suggested that the gamma 316-322 sequence could be involved in platelet adhesion in flowing blood.