The capacities of the adipocyte precursor pools to form new fat cells were compared in the abdominal and femoral adipose tissue regions of obese women. Adipose tissue samples were obtained from 24 females by needle biopsy. The stromal-vascular cells isolated by collagenase digestion were cultured in a chemically defined medium supplemented with 0.5 mumol/l insulin and 0.1 mumol/l cortisol. The extent of adipose differentiation was assessed by determination of glycerol-3-phosphate dehydrogenase (GPDH) activity after 18 days in culture. No significant differences were found between the two depots with regard to mean fat cell diameter and the number of stromal-vascular cells (abdominal vs femoral site: 134,800 +/- 7900 vs 138,800 +/- 6700 cells/g wet adipose tissue, n.s.). However, GPDH activities were significantly higher in cultured cells from the abdominal region as compared to those from the femoral depot (253.1 +/- 40.9 vs 155.8 +/- 21.4 mU/mg protein, P less than 0.01). These results suggest that regional differences exist in the capacity of adipose tissue depots to form new fat cells. This finding may help to understand changes in adipose tissue distribution during adult life.