The humeral defects (Hill Sachs lesion) are considerable factors for glenohumeral instability in epileptic patients. Many surgical procedures have been described for the management of humeral osseous deficiencies, however, epileptic patients still have a very high rate of recurrent dislocation. We reported bilateral large humeral defect due to seizures in epileptic patient which was reconstructed with infraspinatus tendon transfer. A 23-year-old woman who had had glenohumeral dislocation, related to generalized tonic-clonic epileptic seizures, many times before. In computed tomography, there were posterior humeral defects causing instability on both sides. We had performed infraspinatus tendon transfer to reconstruct the humeral defect previously. Upon detecting dislocation, posterior humeral defect was reconstructed with infraspinatus tendon transfer. Despite having had several epileptic seizures since, no redislocation occurred at the 21st month of follow-up. Encouraged with this, we performed the same operation on the right shoulder. There was no redislocation determined at the seventh postoperative month. The reconstruction of the humeral defects by the infraspinatus tendon transfer technique is described in the literature, but we could not find a study about this technique regarding epileptic patients. The technique of infraspinatus tendon transfer with bone block for posterior large humeral defects causing anterior instability is a good choice for epileptic patients.