Epidemiological studies showed incidence of malaria in 8391 plasmapheresis donors of five villages was 4.14%, higher than in those donating whole blood and non--donors. Case--control studies revealed plasmapheresis was a risk factor for malaria infection. Incubation period of plasmapheresis--associated malaria was 16.5 days. Investigation on the blood bank showed there existed cross infection in plasmapheresis. After the close of the blood bank, epidemic of malaria caused by cross infection in plasmapheresis was under control.