In the study, the effect CRF (corticotropin-releasing factor), AVP (argipressin) and NE (norepinephrine) on cAMP formation in cultured rat anterior pituitary cells in vitro was examined and the effect of cAMP formation between normoxia and hypoxia (8%O2) was compared. CRF stimulated the formation of cAMP levels which was correlated with the concentration of CRF in medium. The cAMP levels in medium increased. The intracellular cAMP in cultured anterior pituitary cells was not changed by AVP. The concentration of intracellular cAMP was decreased by NE, but the content of extracellular cAMP was no changed. Hypoxia decreased the stimulating effects of CRF on the cAMP formation in cultured anterior pituitary cells.