In order to study normal and abnormal human megakaryocytopoiesis we modified a glycoprotein Ib dependent megakaryocyte purification technique originally described in guinea pigs. After Percoll density centrifugation, 2 ml bone marrow aspirates were subjected to 3 steps of bovine plasma induced cell clumping, which should selectively agglutinate glycoprotein Ib positive cells. In 13 experiments the resulting samples contained 28-102 x 10(3) megakaryocytes (median 70) with a median purity of 79%. Megakaryocyte recovery ranged from 30-86% (median 51%). The DNA profile showed median values of 10% for 8 N, 44% for 16 N and 43% for 32 N megakaryocytes. The described method is relatively simple, inexpensive and gives results comparable with more elaborate techniques.