Congenital palpebral ptosis is a disease which make problems about surgery timing and surgical method used. A child, three years old, presents partial palpebral ptosis at left eye after congenital paresis of the oculomotor common nerve. Ocular statistical exam underlines one deviation by ten degrees and dorsal vergence by fifteen degrees at left eye. After covering the right eye, the left eye assumes fixation and the upper eyelid elevates. On practise liberality of the right superior muscle at the right eye (Faden method and recoil by 5 mm), which establishes the disparition of the left eye deviation and of the ptosis. Orthoptic exam must direct the decision about the surgical method in these situations.