The localization of parathyroid glands in cases of primary hyperparathyroidism remains a challenge to all endocrine surgeons. Many preoperative localization methods have been tried for localization but proved to be variable in accuracy and not reliable. In this thesis, methylene blue has been used for intraoperative localization of parathyroid glands in ten patients with primary hyperparathyroidism. Methylene blue proved to be safe, effective, economic and reliable in localization of abnormal parathyroid glands intraoperatively.