Pheochromocytoma is a rare tumor that develops from the chromaffin cells of the sympathetic nervous system. Although hypertension is the most common manifestation of pheochromocytoma, it is less common in children than in adults. This condition may be overlooked like in our patient who had an undiagnosed headache for several years. Our patient was admitted to our emergency department due to the increase in headache, which lasted for about 6 years, and a neurological evaluation was performed. Due to the high blood pressure in her follow-up, she was examined further. Abdominal USG revealed a 36x26x27 mm solid lesion in the right adrenal gland with a mild hyperechogenic appearance with a cystic component. With supporting findings in magnetic resonance imaging and high catecholamine levels in blood, she was diagnosed with pheochromocytoma. Our aim in sharing this case is to emphasize the importance of measuring blood pressure in patients accurately and at each examination, evaluating them with percentile charts, and monitoring them closely.