In this study the polymerase chain reaction (PCR) with previously developed oligonucleotide primers was used to detect Leishmania aethiopica in paraffin-embedded skin biopsy specimens. The Leishmania-specific 120 base pair fragment of the kinetoplast deoxyribonucleic acid (kDNA) minicircles has been amplified from all parasitologically or histologically confirmed cases of cutaneous leishmaniasis (CL), as demonstrated by gel electrophoresis and hybridization with L. aethiopica kDNA. Control specimens from patients with skin diseases other than CL were all negative. Using PCR, Leishmania were demonstrated in the skin lesions of 7 cases in a group of 40 patients in whom the parasites could not be demonstrated by histopathology or culture in vitro although lesions were clinically suggestive of CL. These data indicate that PCR, carried out on DNA extracted from formalin-fixed and paraffin-embedded tissue specimens, is a valuable method for the diagnosis of CL, especially in chronic cases where the parasite load in the lesion is low.