Epidermoïd carcinoma is the most common malignant tumor of the lips.They often develop on precancerous lesions. Leukoplasia is the most frequent precancerous lesion. We report a case of a 35 years old man, who suffered from discoid lupus erythematous since 20 years; and wasn't treatedfrom. He consulted for a squamous ulceration of the under lip, developed from one year. The biopsy concluded to an epidermoïd carcinoma.He was treated with surgical excision with reconstruction and homolateral triangular recovery.Keywords: Squamous cell carcinoma, epidermoïd carcinoma, discoid lupus erythematosus, precancerous lesion