Skin ulcers are a commonly encountered problem at departments of tropical dermatology in the Western world. Furthermore, the general dermatologist is likely to be consulted more often for imported chronic skin ulcers because of the ever-increasing travel to and from tropical countries. The most common cause of chronic ulceration throughout the world is probably pyoderma. However, in some parts of the world, cutaneous leishmaniasis is one of the most prevalent causes. Mycobacterium ulcerans is an important cause of chronic ulcers in West Africa. Bacterial infections include pyoderma, mycobacterial infections, diphtheria, and anthrax. Pyoderma is caused by Staphylococcus aureus and/or beta-hemolytic streptococci group A. This condition is a common cause of ulcerative skin lesions in tropical countries and is often encountered as a secondary infection in travelers. The diagnosis is often made on clinical grounds. Antibacterial treatment for pyoderma should preferably be based on culture outcome. Floxacillin is generally active against S. aureus and beta-hemolytic streptococci. Infection with Mycobacterium ulcerans, M. marinum, and M. tuberculosis may cause ulcers. Buruli ulcers, which are caused by M. ulcerans, are endemic in foci in West Africa and have been reported as an imported disease in the Western world. Treatment is generally surgical, although a combination of rifampin (rifampicin) and streptomycin may be effective in the early stage. M. marinum causes occasional ulcerating lesions in humans. Treatment regimens consist of combinations containing clarithromycin, rifampin, or ethambutol. Cutaneous tuberculosis is rare in travelers but may be encountered in immigrants from developing countries. Treatment is with multiple drug regimens consisting of isoniazid, ethambutol, pyrazinamide, and rifampin. Cutaneous diphtheria is still endemic in many tropical countries. Cutaneous diphtheria ulcers are nonspecific and erythromycin and penicillin are both effective antibacterials. Antitoxin should be administered intramuscularly in suspected cases. Anthrax is caused by spore-forming Bacillus anthracis. This infection is still endemic in many tropical countries. Eschar formation, which sloughs and leaves behind a shallow ulcer at the site of inoculation, characterizes cutaneous anthrax. Penicillin and doxycycline are effective antibacterials. Cutaneous leishmaniasis is caused by different species belonging to the genus Leishmania. The disorder is one of the ten most frequent causes of skin diseases in travelers returning from (sub)tropical countries. The clinical picture is diverse, ranging from a painless papule or nodule to an ulcer with or without a scab. Treatment depends on the clinical manifestations and the species involved.Sporotrichosis, chromo(blasto)mycosis, and mycetoma are the most common mycoses that may be accompanied by ulceration. Infections are restricted to certain regions and often result from direct penetration of the fungus into the skin. Anti-mycotic treatment depends on the microorganism involved. The most common causes of infectious skin ulceration encountered in patients from tropical countries who present at a department of tropical dermatology are reviewed in this article.