Genital ulcers can be caused by infections such as herpes simplex virus, syphilis, chancroid, and lymphogranuloma venereum or by non-infectious causes. Clinical diagnosis of the cause is difficult so tests for syphilis, herpes simplex virus, and chancroid should be considered in all patients. Treatment depends on the suspected cause but herpes simplex virus is usually treated with oral acyclovir and syphilis with intramuscular penicillin G benzathine.