One dose of clofibride (Cf) is administered, after sacrifice of normal fasting rat, in vitro: 2 mg/100 mg adipocytes in 2 ml medium. Lipolysis is studied by the way of glycerol release: micromoles/90 minutes/100 mg total lipids, without or with hormones: epinephrine (10 micrograms/ml), insulin (10(-3) U.I./ml), or association of both. 1. In vitro adjunction of clofibride alone, reduces basal lipolysis (p less than 0,05). 2. Clofibride strongly limits the effects of lipolysis stimulation induced by epinephrine (p less than 0,01). 3. However, it does not increase the discrete antilipolytic effect of insulin, and does not reduce significantly lipolysis induced by the epinephrine + insulin association. Clofibride hypolipaemic effects could be due, partially, to a reduction of hormono-dependent lipolysis.