The purpose of this study was to determine the effects of hCG on cellular cAMP levels in gastric adenocarcinoma cells(SGC-7901). Radioimmunoassay was used. The results showed that hCG obviously increased cAMP levels in SGC-7901 cells in a dose-dependent and time-dependent manner. When the concentration of hCG increased from 10(-11) mol/L to 10(-6) mol/L, the cellular cAMP levels increased from about 2.1 pmol/mg protein to about 10 pmol/mg protein and were significantly different from the control(P < 0.01). These results suggest that hCG possibly exerts its effects on gastric cancer cells by activating adenylyl cyclase/cAMP signal transduction pathway.