Trypomastigotes grown in fibroblast cell (L-cell) culture were more effectively and more rapidly separated from other cells on a CM-cellulose column with culture medium (MEM with 10% calf serum) for elution instead of phosphate-saline-glucose buffer (PSG). This effective separation was shown to be due to the presence of serum. Trypomastigotes weakly adhered to CM-cellulose resin by the tip of the body (mainly the flagellar tip) when they were suspended with CM-cellulose resin in PSG. Serum seemed to disturb the adhesion of trypomastigotes to the resin, but not the adhesion of amastigotes and fibroblast cells. Therefore, only trypomastigotes were rapidly eluted from a CM-cellulose column in the presence of serum.