The symptoms of Systemic Lupus Erythematosus (SLE) may include altered mental function. The present study sought to determine whether the psychiatric disorders are due to the disease itself or to the stress of having a chronic disease. Forty-five SLE patients attending outpatient clinics at the Port-of-Spain General Hospital in Trinidad were compared with two control groups: patients with chronic debilitating diseases similar to SLE in terms of chronicity and treatment (n = 44) and non-diseased individuals (n = 48). The Structured Clinical Interview for DSM III-R was used to identify psychiatric disorders. Both the SLE and the chronic illness groups had more psychiatric illness (44% and 39%, respectively) when compared with the non-diseased controls (2%) (p < 0.001). Major depression was the most common diagnosis among both diseased groups. However, psychotic illnesses (schizophrenic-type psychosis and bipolar disorders) were more prevalent in the SLE group (11.1% vs 0%, p = 0.02). These results indicate that major depression in SLE may be related more to the effects of a chronic illness than to SLE itself. However, the occurrence of psychotic symptoms may be related to SLE disease and needs further study.