Marcus Gunn syndrome or unilateral trigemino-oculomotor syncinesis is a very rare autosomal dominant genetic disorder characterised by a combination of congenital ptosis and mandibulopalpebral syncinesis during certain mandibular movements. We report a series of two cases of children with Marcus Gunn syndrome. Case 1: A 5-year-old boy with no previous pathological findings presented with unilateral ptosis of the left upper eyelid at the age of 4 months. His visual acuity was 10/10 in right eye on the right and 5/10 in left eye. Second case: a 7-year-old girl, brought in by her parents for a ptosis of the left eye noted at birth. This is a 7-year-old girl brought in by her parents for ptosis of the left eye, diagnosed at birth. She had no particular pathological antecedents. Her visual acuity was 10/10 in right occlusion and 3/10 in left occlusion. Both children had undergone sectioning of the superior levator muscle with frontal suspension using prolene sutures, with good progression, followed by total optical correction and treatment of the amblyopia.