Rat hepatocytes were cryopreserved in hormonally-defined medium (HDM) containing either fetal bovine serum (FBS), glycerol, dimethyl sulfoxide (DMSO), sucrose or a mixture of these as a cryoprotectant. The best survival was with 10% (v/v) DMSO containing 30% (v/v) FBS using 5 x 10(5) hepatocytes ml(-1) at -70 degrees C for 5 d on type I collagen-coated dishes. After thawing, the cell viability was 81% determined by the MTT-test. The cryopreserved hepatocytes had the capacity of albumin synthesis similar to hepatocytes without cryopreservation. This result shows that cryopreservation of rat hepatocyte can be used for the evaluation of hepatic functions.