Sera from 86 Colombian patients with parasitologically confirmed cutaneous leishmaniasis were studied by immunoblot analysis in order to identify a specific pattern for Leishmania infection. A soluble extract of Leishmania panamensis was used as the antigen. Sera from patients with Chagas' disease and sera from patients with no record of infection with trypanosomatids were also studied. The sera from patients with cutaneous leishmaniasis specifically recognized fractions of 120 kDa (76.7%), 123 and 129 kDa (69.7%), 138 kDa (61.6%), 141 kDa (53.4%), and 78 kDa (44.1%). No band common to all patients infected with Leishmania parasites was found at the time of diagnosis. Likewise, the pattern of immunoblot change after the patients were treated and apparently cured with meglumine antimoniate (Glucantime) was studied by evaluating sera pretreatment and 1 year posttreatment. Only minor changes in the color intensity at the same serum dilution between pre- and posttreatment sera were found, although the antibody titers by indirect immunofluorescence were negative for the posttreatment sample. This study shows that Western blot analysis is a more sensitive test for the detection of anti-Leishmania antibodies. However, the importance of whether the presence of antibodies correlates with the presence of Leishmania antigens could not be resolved by the data obtained from this study.