Patients with primary immunodeficiencies have a high incidence of autoantibodies, mainly of no clinical significance. It has recently been suggested that patients with a combined IgA-IgG2 deficiency have more autoantibodies than those patients with isolated deficiencies. We have studied 42 patients with selective IgA deficiency, nine with isolated IgG2 deficiency and 13 with combined IgA-IgG2 deficiency, and have found that the combined IgA-IgG2 deficiency has no influence on autoantibody prevalence, except for anti-IgA antibodies. The presence of chronic respiratory infections (a clinical feature commonly associated with both selective IgA and IgG2 deficiencies) is unrelated to the prevalence of autoantibodies. The most frequent autoantibodies found are anti-IgA and anti-cardiolipin. Most of the autoantibodies have been found to be devoid of actual clinical significance. Only three patients had overt autoimmune disease.