The effects of oestrogen (OE), progesterone (P) and oestrogen plus progesterone (OEPP) on uterine lipids of adult ovariectomized rats were studied. Administration of gonodal hormones brought about considerable alterations in total lipids, mainly due to an increase in phospholipids and glycerides in the case of OE and P groups. Even though the total cholesterol remained unaltered, a marked alteration in its fractions was evident in all the groups. Oestrogen seems to decrease all the glyceride classes while progesterone induces accumulation of triglycerides with concomitant decrease in mono- and diglycerides. Individual classes of phospholipids show marked alterations in their distribution in all the groups studied.