Hydroxyeicosatetraenoic acids (HETEs) have numerous physiological effects, including modulation of cell proliferation and differentiation. However, little is known about the selective effects of HETE enantiomers on cell proliferation and cell signalling pathways involved in the regulation of cell growth. Furthermore, information on epithelial and endothelial cells growth is controversial. Recently, we demonstrated that 5-, 12-, and 15-HETE are involved in the control of 3T6 fibroblast growth though serine/treonine Akt/PKB (Akt) pathway. Here we examined the participation of both enantiomers (S and R) of HETEs in the control of 3T6 fibroblast growth. Our results show that HETEs (5-, 12-, and 15-HETE) are enantioselective on protein and DNA synthesis and 3T6 fibroblast growth. Furthermore, we observed that 12(S)-HETE induces the enhancement of cAMP and intracellular calcium concentration, whereas 12(R)-HETE was uneffective. Our findings also demonstrated that 12(S)-HETE exerts these effects through enantiospecific interactions with a cellular element, probably a plasma membrane receptor coupling to a pertussis toxin-sensitive protein G. Moreover, these elements may be involved in the activation of mitogen-activated protein kinase pathways which induce the enhancement of cyclin D(1) levels.