We reviewed the clinical features of 150 patients with acquired pure red cell aplasia (PRCA) in Japan. There were 35 patients with acute type and 115 with chronic type PRCA. Of the acute PRCA patients, 17 had human parvovirus B19 infection. Drug-induced PRCA was demonstrated in 7 patients. Of the 115 patients with chronic PRCA, 51 patients were classified as primary and 64 cases were associated with miscellaneous diseases such as thymoma, a variety of hematological disorders and collagen diseases. Among the hematological disorders, PRCA was most frequently seen in granular lymphocyte proliferative disorders (GLPD). The erythroid colony growth patterns from bone marrow were variable. The serum erythropoietin level was high in most patients. Various kinds of treatment were tried for the chronic PRCA cases. Cyclosporin A (CyA) was the most effective form of treatment and the response rate was 82% (31/38). Twenty-three of 37 patients (62%) responded to bolus methylprednisolone therapy. The largest number of patients were treated with oral prednisolone, and the therapy was effective in 27 of the 55 (49%). The response rate to cyclophosphamide was only 29% (5/17), but in combination with prednisolone, half of the patients (7/14) responded to the therapy. CyA is recommended as the first-line therapy for acquired chronic PRCA.