Two hundred twenty-six consecutive adult patients with cutaneous leishmaniasis in Colombia were treated with Glucantime and 81% were cured. The 19% who failed treatment had received a statistically significant lower total amount of antimony (354 mg/kg) than those who were cured (405 mg/kg) (P = 0.002). Thirty-nine of the failures were re-treated with Glucantime and 59% were cured. This large experience on initial and re-treatment cure rates probably represents the values found in clinical practice. In this series, parasite resistance may have been induced by the relatively low initial dose of antimony administered to some patients.