The dexamethasone suppression test (DST) was performed in 18 patients (11 women and 7 men) who met the DSM III-R criteria for obsessive-compulsive disorders (OCD), and in 20 healthy volunteers (12 women and 8 men). At 4.00 p.m., following dexamethasone administration, 5 patients (27.7%) and 1 healthy subject (5%) displayed plasma cortisol values well above the cut-off value of 50 ng/dl. A significantly different sex ratio was observed between suppressor and nonsuppressor patients with OCD (chi 2 = 4.40, p less than 0.03), because all nonsuppressor patients were male. Compared to the suppressors, nonsuppressor patients with OCD did not differ in any of the clinical and demographic variables investigated. Moreover, in our patient sample, the mean +/- SD total Hamilton Depression Rating Score (HDRS) was 14.8 +/- 2.5, and none of the nonsuppressors with OCD had a total HDRS greater than 17. These data suggest that a subgroup of OCD patients, particularly males, may escape the DST independently from the coexistence of depressive features.