Effects of 4 progestogens at equal dosages (5 mg/kg/day) on lipid metabolism and plasma glucose levels of adult female rats were compared. The 4 progestogens studied were progesterone (P) by SC injection, and megestrol acetate (MEG), norethindrone acetate (NOR), and nomegestrol acetate (NOM) PO. MEG, a 17 alpha-hydroxyprogesterone derivative, induced significant increases in glucose, total and high-density lipid (HDL) cholesterol, triglyceride, and phospholipid plasma levels. Treatment with NOR, a 19-nortestosterone derivative, resulted in a reduced gain in body wt and in a marked decrease in all plasma lipid parameters. The 19-norprogesterone derivative NOM, like P, did not alter lipid or glucose metabolism, despite a significant increase in body wt gain. In particular, no reduction in the HDL cholesterol level occurred. Plasma and tissue lipolytic activities remained unchanged. The results of this study confirm interest in the therapeutic class of 19-norprogesterone-derived progestogens, exemplified by NOM, with respect to their lack of metabolic side effects.