A 2-year and 5-month-old boy was admitted to Okaya municipal hospital because of low grade fever and reddish-brown urine soon after an outside walk in November, 1994. Direct Coombs test was negative, but indirect Coombs test positive. Both sugar water test and Ham test were negative. A diagnosis of paroxysmal cold hemoglobinuria (PCH) was made by Donath-Landsteiner (D-L) test which showed the presence of a high amount of anti-P specific IgG and IgM of D-L antibody. Serological tests for syphilis were negative. Cold agglutinin titer and mycoplasma antibody titer was X 128 and X 80, respectively. A bone marrow specimen exhibited pronounced hemophagocytosis. Serum INF-gamma and M-CSF level were normal (less than 5 pg/ml and 1007 units/ml, respectively). These results suggest that hemophagocytosis in this case is not due to hemophagocytic syndrome.