OBJECTIVE To study the profile of associated autoimmune diseases in a series of patients with systemic lupus erythematosus (SLE) and see if such associations are linked to IgA deficiency. METHODS Two hundred eighty-one patients with SLE were studied for Ig A levels by nephelometry. Levels equal to or under 0.05g/dL were considered as IgA deficiency. Epidemiological and clinical data, including the presence of associated autoimmune diseases, were extracted from the patient's charts. RESULTS Ig A deficiency was found in 6% of the patients. In 30.2% of SLE patients, there was at least one more autoimmune disease; Hashimoto thyroiditis and Sjögren's syndrome were the most common. No association between the occurrence of associated autoimmune disease with IgA deficiency was found. CONCLUSIONS There is a high prevalence of autoimmune diseases associated with SLE. IgA deficiency does not affect the presence of these associations.