In 80 patients with painful purulent penile ulcers who attended the outpatient service of Middle Road Hospital in Singapore, Haemophilus ducreyi was isolated from 18 (22%), herpes simplex virus type 2 from nine (11%), and Neisseria gonorrhoeae from eight (10%). Primary pathogens were not isolated from 45 (57%) men. Painful purulent penile ulcers were more common in uncircumcised men, and patients had often acquired the disease after sexual intercourse with prostitutes in Singapore.