In groups of obese men and women with an abdominal type of fat distribution, we measured fat cell size, lipoprotein lipase (LPL) activity and lipolysis stimulated by norepinephrine (NE) or isoproterenol (ISO) or inhibited by insulin, in subcutaneous abdominal and retroperitoneal (nonportal), as well as in omental and mesenteric (portal) adipose tissues. Both men and women had large intraabdominal adipocytes. No differences were found between the two groups of obese subjects in fat cell size or LPL activity in the different adipose tissue regions. Women had as high NE- or ISO-stimulated lipolysis in the portal as in nonportal fat tissues, equally high as that found in men. In comparisons with a previous study in nonobese men and women, these results show an increased fat cell size in all tissues in obese women and an increased lipolysis in portal tissues in obese women and in nonportal tissues in obese men. Taken together, these results might mean that obese men and abdominally obese women have a large potential to release free fatty acids (FFA) from intraabdominal depots. This might be followed by metabolic derangements seen in such groups of obese subjects.