A selective IgA deficiency (SD IgA) appears in a 0.15% of the population, being more frequent in autoimmune diseases. We present here eight patients presenting this association who were diagnosed at the Rheumatology Department during a period of eight years. Five patients suffered Juvenile Chronic Arthritis (JCA), two patients Rheumatoid Arthritis (RA) and one Systemic Lupus Erythematous (SLE). There were to cases of familiar deficiency. There was not a relationship between SD IgA and treatments used. There is an important association between SD IgA and JCA (4.27% prevalence). In the other two conditions, however, the association could be casual.