Aims/hypothesis. Adipose tissue-derived tumour necrosis factor-α (TNF-α) has been implicated in the insulin resistance observed in animal models of obesity. Moreover, TNF-α has inhibitory effects on adipocyte differentiation. Glucocorticoids play important roles in the regulation of insulin sensitivity and adipose tissue distribution. We therefore studied the effect of dexamethasone on TNF-α expression and adipocyte differentiation in human PAZ6 cells. Methods. The expression of TNF-α and adipocyte differentiation markers was assessed by reverse-transcription polymerase chain reaction in PAZ6 cells. Results. In cells cultured for 15 days in the presence of dexamethasone, adipocyte differentiation marker expression was higher and TNF-α expression was lower than in cells cultured in the absence of dexamethasone. The presence of dexamethasone was necessary during the whole period of differentiation because removal of dexamethasone during the second week resulted in poorly differentiated adipocytes that express higher levels of TNF-α.