Human erythrocytes parasitized with Plasmodium falciparum, obtained from in vitro continuous cultures and stored at -185 degrees C and at -70 degrees C for several months, were successfully recovered. Ten per cent glycerol or 10% dimethyl sulphoxide in growth medium RPMI 1640 were used and found equally effective as cryopreservatives. This simplified method does not require centrifugation or special media before storage or after recovery of the parasites. The viability of the parasites is monitored in vitro by initiating new continuous cultures.