A 60-year-old woman treated by maintenance haemodialysis refused to take part of the usual vitamin supplements for many years. After an intercurrent illness with profound malnutrition, she developed a paranoid delirium and some behavioural disorders; concomitant diarrhoea and a skin rash were noted. Parenteral nicotinamide (500 mg/day) resulted in a complete recovery from the mental disorders after five days. Other causes of mental disturbance as a result of dialysis could be ruled out. However an asymptomatic underlying hypothyroidism may have been one of the conditioning factors as well as the failure to administer nicotinamide supplements during an acute illness. Neurological pellagra could thus be considered as a rare but reversible cause of mental disorders in patients on maintenance haemodialysis.