Cutaneous leishmaniasis caused by Leishmania tropica has long been associated with Aleppo in Syria. For 20 years up to the mid-1980s, the number of cases reported annually in the city and environs has remained low, not exceeding a few hundred. Since then, there has been a sudden increase to several thousand cases reported each year. The increase seems too great and too sudden to be attributable to improved case detection. Insecticide spraying, begun in 1991, was followed by a reduction in number of cases in 1992, but numbers increased subsequently in spite of continued spraying. The cases are found mainly in areas undergoing development outside the old centre of the city, and may be associated with poor waste disposal and heaps of construction waste.