Skeletal derangements occur quite often in patient with primary hyperparathyroidism (PHPT). We inves- tigated parathyroid and bone imagings in 59 cases of pathologically proven PHPT. Forty-nine cases were pathologi- cally proven parathyroid adenomas; 8 presented hyperplasia and the other 2 were adenocarcinomas. Parathyroid im- aging (early phase imaging, EPI) was conducted at 30 min after injecting 740~925MBq 99m Tc-MIBI and 2~3h later (delayed phase imaging, DPI) separately. The following thyroid imagings were performed at the same posture 10 min after intravenous injection of 74~111MBq 99m TcO4 . The - 99mTc- MIBI subtraction imaging data were obtained by subtracting thyroid imaging from that of DPI. Among 49 cases of proven hyperparathyroid adenoma 45 yielded positive imagings. Eight cases with hyperplasia gave negative results. The results were positive in 2 cases of parathyroid adenocarcinoma. Results of 99m Tc-MDP/bone imaging: 35 cases of hyperparathyroid adenocarcinoma (disease duration 1-6 months) showed normal bone images, while 14 cases showed superscan images, course being 4~12 months. Bone imaging for 2 cases of adenocarcinoma showed multiple, radioactive aggregated foci (brown tumor imaging); course lasting 10~24 months. The results of bone imaging in 8 cases of hyperplasia/ hyperparathyroidism were normal. It was concluded that diagnostic accuracy for parathyroid was 79.6% and for parathyroid adenoma was 91.8%, and the technique has no diagnostic value for hyperplasia. The 99m Tc-MDP / bone imaging results for PHPT can be classified into three categories, i.e. normal, superscan and brown tumor. The imaging results correlated well with the different categories and degrees of bone damage, the duration of clinical course and the pathological types. Therefore, it’s important to use bone imaging data in association with therapy to reflect the stage and progress of PHPT. Skeletal derangements occur quite often in patients with primary hyperparathyroidism (PHPT). We inves- tigated parathyroid and bone imagings in 59 cases of pathologically proven PHPT. Forty-nine cases were pathologi- cally proven parathyroid adenomas; 8 presented hyperplasia and the other 2 were The following thyroid imagings were performed at the same, respectively. The following thyroid imagings were performed at the same The - 99mTc - MIBI subtraction imaging were harvested by subtracting thyroid imaging from that of DPI. Among 49 cases of proven hyperparathyroid adenoma 45 yielded Eight cases with hyperplasia gave negative results. The results were positive in 2 cases of parathyroid adenocarcinoma. Results of 99m Tc-MDP / bone imaging: 35 cases of hyperparathyroid adenocarcinoma (disease duration 1-6 months) showed normal bone images, while 14 cases showed superscan images, course being 4 ~ 12 months. Bone imaging for 2 cases of adenocarcinoma showed multiple, radioactive aggregated foci (brown tumor imaging); course lasting 10 ~ 24 months. The results of bone imaging in 8 cases of hyperplasia / hyperparathyroidism were normal. It was done that diagnostic accuracy for parathyroid was 79.6% and for parathyroid adenoma was 91.8%, and the technique has no diagnostic value for hyperplasia. The 99m Tc-MDP / bone imaging results for PThe imaging results correlated well with the different categories and degrees of bone damage, the duration of clinical course and the pathological types. HPT can be classified into three categories, ie normal, superscan and brown tumor. in association with therapy to reflect the stage and progress of PHPT.