Secondary and tertiary hyperparathyroidism is an important problem of chronic kidney disease. Brown tumor is a benign, unusual, reactive lesion as a result of disturbed bone remodeling, from long-standing increase in parathyroid hormone level. Brown tumors may cause morbidity due to pressure symptoms on neural structures and spontaneous bone fractures. Herein, we presented a peritoneal dialysis patient with tertiary hyperparathyroidism under calcand calcitriol treatment for 4 years due to refusing of the parathyroidectomy operation. She admitted to hospital for sudden onset back pain with difficulty in gait and walking, and imaging studies showed an expansile mass lesion in the thoracic spine. She was operated for mass and diagnosed with brown tumor. After operation, she lost the ability of walking than become paraplegic and she underwent rehabilitation program. Preventive measures including calcitriol and cinacalcet may cause a modest decrease in parathyroid hormone levels but it should be remembered for the development of bone complications such as brown tumor formation in patients with moderate elevated PTH levels, especially those with tertiary hyperparathyroidism. Parathyroidectomy should be performed without delay in these cases.