Alopecia areata is an autoimmune disease causing patchy hair loss, which occurs with an increased incidence in patients with lupus erythematosus. We report a 27-year-old African-American female with systemic lupus erythematosus and alopecia areata, whose biopsy showed a marked increase in mucin in the deep dermis and subcutis. Archival biopsies of alopecia areata were then reviewed to see if this finding occurs in patients without systemic lupus. Of 13 recent biopsies diagnostic of alopecia areata, we detected deposition of mucin in 3 (23%), but all mild in degree and in a superficial location. We speculate that the marked deposition of mucin in this patient's biopsy of alopecia areata may be related to her underlying systemic lupus, and that the presence of marked, deep dermal deposition of mucin might serve as a diagnostic clue for the presence of underlying systemic lupus in patients with alopecia areata.