Following the second series of intravenous human immunoglobulins (IVIg; 0.4 g/kg) prescribed to treat a sensorimotor polyneuritis, a 28-year-old woman developed pompholyx that recurred after each of the following monthly treatments with IVIg. During the administration of the 10th series, the patient developed a typical baboon syndrome. Immunohistochemical studies of a skin biopsy revealed an unexpected epidermal expression of P-selectin, usually expressed by endothelial cells. Patch, prick and intradermal tests performed with IVIg on the back, arms and buttocks gave negative results on immediate and delayed readings. IVIg were re-administered, with the informed consent of the patient, and induced a generalized maculopapular rash. This is the first reported case of baboon syndrome induced by IVIg. Although extensive skin testing was performed, all test sites remained negative. We wonder whether IVIg could reproduce immunological mechanisms involved in the 3 types of systemic contact dermatitis (pompholyx, baboon syndrome and maculopapular rash), including the epidermal expression of P-selectin.