- January 2007Psoriasis is a common skin disease that affects 1–3% of the general population. Systemic lupus erythematosus is much less common than psoriasis. Its overall prevalence in the United States ranges be-tween 14.6 and 50.8 cases/100,000 adults. Although SLE has been described in as-sociation with other autoimmune diseases such as rheumatoid arthritis, scleroderma, mixed connective tissue disease, autoim-mune thyroid diseases, pernicious anemia and others , the coexistence of these two diseases is very rare [2-4]. A PubMed search of the English-language medical literature showed no previously published cases of psoriatic arthritis associated with SLE. We report the first two cases of patients suffering from both psoriatic arthritis and SLE.