The effect of 15-Mt-PGF2 alpha on CCl4-induced injury of primary cultured hepatocytes was studied. 15-Mt-PGF2 alpha treatment (2 mg/L) significantly decreased CCl4 (10 mmol/L)-induced damages of primary cultured rat heptocytes as indicated by decreases GPT and GOT leakage and LPO production. 15-Mt-PGF2 alpha significantly promoted 3H-uridine incorporation into RNA and [3H]-thymidine incorporation into DNA of the rat hepatocytes. Cytopathology study showed that 15-Mt-PGF2 alpha attenuated damages of mitochondria, endoplasmic reticulum and ribosome caused by CCl4. 15-Mt-PGF2 alpha appeared to maintain the stability of rat hepatocytes by inhibiting lipid peroxidation. These results indicated that 15-Mt-PGF2 alpha has notable protective effect on primary cultured rat hepatocytes against CCl4-induced damage by reducing lipid peroxidation and promoting synthesis of RNA and DNA.