The authors describe a case of pigmentation of the gums occurring after therapy with hydroxychloroquine. A twenty-eight-year-old woman with discoid lupus erythematosus was treated only with hydroxychloroquine. After seven months of this therapy, a diffuse bluish-gray pigmentation was apparent on the vestibular surface of the gums of both dental arches. No pigmented lesions were noticed on either the skin or the nails.