Actinomycosis is a chronic suppurative granulomatous infection caused by gram positive bacterium. Enfection especially affects the head, neck, thorax and abdomen. Primary cutaneous involvement is uncommon and has an association with trauma and local ischemia. We present one such case of primary cutaneous actinomycosis on the elbow of a 68 year old man with diabetes and external trauma. This patient was admitted to our clinic with a 10-12cm size blue-purple plaque. Skin biopsy revealed the characteristic 'sulphur granules' of actinomycosis in the deep dermis After the diagnosis, initially he was treated with penisilin and cotrimaxazol with a little effect. Treatment was continued with amoksisilin and cotrimaxazol and he respond to this medical treatment partially. After this medical therapy skin graft operation was performed. Lesions relapsed six months later. Medical therapy was repeated and still continues