Sex steroid hormones are important factors in the determination of fat distribution and accumulation. The aim of this study was to investigate the effect of testosterone (T), 17- estradiol (17E) and progesterone (P) on adrenergic receptor (AR) gene expression in 3T3-L1 preadipocytes and adipocytes, and their relation to the proliferation and differentiation processes. Our data clearly show that _2A-AR was the highest AR subtype expressed in preadipocytes, whereas in mature adipocytes was by far ₃-AR. In the differentiation process to adipocytes, _2AAR expression was decreased to 0.3 fold (p<0.01), whereas ₃-AR was upregulated by 578 fold (p<0.001), compared to preadipocytes. In addition, the expression of _2A-AR in preadipocytes was increased upon incubation with T, 17E and P, and a stimulation of proliferation was also observed in 17E and P treated cells. In mature adipocytes, 17E and P enhanced both _2A- and ₃-AR gene expression - although the effects on ₃-AR mRNA levels could be more relevant as ₃-AR was the most highly expressed -, while T only increased _2A-AR mRNA levels. Leptin and aP2/FABP mRNA levels were higher after 17E and P treatment, possibly indicating a proadipogenic effect of these hormones. In conclusion, this study indicates that AR gene expression is affected by these hormones both in preadipocytes and adipocytes, which could have potential importance when considering the role of ARs in the mechanisms underlying the genderrelated differences in adipose tissue regional distribution.