It has been proposed that differences in adipocyte function and/or metabolism between obese and lean individuáis may manifest themselves in functional adipose tissue abnormalities that lead to metabolic disorders in obesity. We studied lipogenesis and lipolysis of omental adipocytes from obese (OB) and non-obese (NOB) humans. The specific activity of the lipogenic marker enzyme G3PDH was 50% lower in total adipocytes of OB compared to that of NOB subjects. Omental adipocytes from OB subjects also had lower basal lipolytic levéis, and a lower lipolytic response to p-adrenergic stimulus. Cholesterol depletion of adipocyte plasma membrane using methyl β-cyclodextrin caused a lipolytic effect on adipocytes of both groups together, but when obese and lean subjects were analyzed separately, the response was significant only in the obese. We present evidence of a different lipogenic and lipolytic profile in obese individuáis' omental adipocytes, and propose a relevant role of plasma membrane cholesterol, where the impact of its removal in OB and NOB adipocyte lipolysis differs.