Based on very promising results obtained in preliminary in vivo experiments as well as thorough investigations on the metabolism, dermal absorption and non-toxicity of Arnica tincture against cutaneous Leishmaniasis, the Colombian authorities have given their consent to conduct an observational study with human CL patients. The study is conducted by ResNet NPND member Sara M. Robledo (Medellin, Colombia) as part of a cooperation project with T.J. Schmidt (Münster, Germany).