AbstractTwo apheresis methods used to collect hematopoietic stem cells from peripheral blood were compared in eight patients with a variety of malignancies. The standard lymphocyte collection method was alternated with the counterflow centrifugation or lymphocyte surge protocol. The number of clonogenic cells (CFU‐GM and BFU‐E), the red cell volume, and the number of mononuclear cells in each collection were assessed as well as the changes in circulating leukocytes, platelets, and blood hemoglobin produced by each apheresis procedure. There was no statistically significant difference found in the number of clonogenic cells collected with either method, but the number of mononuclear cells collected with the standard procedure was significantly higher (P= 0.001). The red cell volume collected with the standard procedure was significantly higher, (P= 0.0001), but corrected for the number of mononuclear cells the difference was not significant. The counterflow centrifugation apheresis produced significantly less thrombocytopenia (P= 0.005). The counterflow centrifugation apheresis procedure used collected fewer mononuclear cells than the standard procedure, however, with less red cell contamination but a comparable number of CFU‐GM and BFU‐E in four hour apheresis procedures. Each collection method resulted in a comparable amount of anaemia and leukopenia but the lymphocyte surge method produced less thrombocytopenia following the col