Hydroxyurea is an antineoplasic agent usually used in myeloproliferative syndromes, but also in other benign pathological circumstances. Several dermatological manifestations have been recognized as being secondary to its prolonged use, of which the leg ulcer. We report an observation. Mrs. L.D, 47 years, were hospitalized on July 14, 2004 for an ulcer of left ankle in a feverish context. She was followed since 2001 for a chronic myelogenous leukaemia, and took hydroxyurea at a rate of 1500 mg per day, with a good clinical and hematologic answer. She presented a painful ulcer compared to the left external malleolus, with purulent bottom, without signs of vascular attack. The hemogram showed a hyperleucocytosis with 24.000 white elements/mm3 with neutrophilic polynucleosis. Pus sample on the ulcer showed Pseudomonas aeruginosa, and the blood culture was negative. The cure was obtained two months after stopping hydroxyurea. The ulcer of leg related to hydroxyurea is a seldom described pathology. Its occurrence imposes the final stop of the treatment.