Human lymphocytes, granulocytes and monocytes were purified from normal human peripheral blood, using Ficoll-Conray gradient sedimentation and glass adherent activity of monocytes. The characteristics of surface structure among them were easily shown by SEM observation, e.g. monocytes had ruffled, granulocytes had ridge-like and lymphocytes had finger-like projections on their surface. Most of purified SRBC-RFL (T-cells) had smooth surface structure. However, the approximate ten percentage of them showed the villous one. A MRBC-RFL which belonged to surface immunoglobulin bearing cells (B-cells), showed the smooth one. It was concluded from the results that it was difficult to judge only from their surface characteristics whether the lymphocytes were T-or B-cells. Erythrophagocytosis by human monocytes bia Fc-receptor consisted of attachment, engulfment and cytolysis. SEM observation clarified the surface morphological changes of monocytes and erythrocytes in each stage. This phenomenon indicated that erythrophagocytosis might play a role in hemolysis of patient with autoimmune hemolytic anemia.