The sexually transmitted diseases chancroid, lymphogranuloma venereum and granuloma inguinale should be familiar to physicians who care for patients at risk. The mucocutaneous manifestations of these three diseases must be distinguished from the lesions of other venereal diseases, such as primary syphilis and genital herpes simplex. Human immunodeficiency virus (HIV) infection should always be considered in patients with any venereal disease, since sexually transmitted diseases often occur together. Furthermore, the genital erosions that occur in patients with these three disorders may predispose them to HIV infection.