We compared the rate of DST non-suppression in two samples of 26 Brazilian and 26 Belgian female depressive patients, matched for age, diagnostic subtype and severity of depression. This rate was significantly lower in São Paulo than in Liège (P = 0.04). The differences observed in DST can be explained by the complexity of familial, personal and clinical factors. A role of a latitude effect through melatonin secretion on adrenocortical function of depressed patients is also suggested.