Congenital unilateral lower lip paralysis(CULLP) is a congenital condition characterized by inversion and decreased depression of the affected lower lip while opening the mouth. CULLP is caused by congenital palsy of the marginal mandibular branch of the facial nerve due to abnormal development, or hypoplasia of the depressor anguli oris muscle. We present here cases of congenital unilateral lower lip palsy in three patients. This paper presents a balancing technique for this lower lip asymmetry that involves resection of the depressor labii inferioris on the non-paralysed side.Two patients referred to our hospital for assessment of lower lip paralysis. For the treatment, depressor labii inferioris resection on the nonraralyed side were performed under local anesthesia. Patients felt their lower lip was asymmetrical at rest prior to surgery and patients were completely improved by the muscle resection. Depressor labii inferioris resection is a simple and effective procedure for the treatment of marginal mandibular nerve palsy. The results are permanent and predictable. Lower lip symmetry is produced both at rest and with facial animation, without causing a functional deficit.