Context: In Western countries, most primary hyperparathyroidism (PHPT) patients are asymptomatic.The incidence of parathyroid cancer is as low as 1% but is trending upward.The clinical outlook of PHPT in Chinese patients is unclear.Objective: Describing the changing clinical patterns of benign and malignant PHPT in Chinese patients from 2000-2010.Design and Setting: This was a cross-sectional study.Subjects: A total of 249 PHPT patients were studied.Main Outcome Measures: The clinical manifestations and biochemical abnormalities of PHPT were analyzed.Results: 61.4% of our PHPT patients were symptomatic, but the asymptomatic PHPT has increased from < 21% in 2000-2006 up to 42.4%-52.5% in 2007-2010.48.9% of asymptomatic patients came to our center due to elevation of serum calcium levels, another 46.9% because of parathyroid nodule(s) incidentally discovered by thyroid ultrasonography with a steady increase from 18.3% before 2007 to 35.7% in 2007-2008, and 61.5% in 2009-2010.Serum calcium and PTH concentrations over 2.77 mmol/L (Area under the curve, AUC, 0.995, P<0.001) and 316.3 pg/dl (AUC 0.842, P<0.001), respectively, are responsible for symptom development.The occurrence of parathyroid carcinoma was as high as 5.96%, but a trend downward from 10.53% to 4.44% was observed.Conclusion: The overall clinical and biochemical features of PHPT in Chinese patients are still classical, but the disease is now evolving into a more asymptomatic type.The incidental parathyroid lesion captured by routine neck ultrasonography was the leading cause for such a dramatic change.The high incidence of parathyroid carcinoma is now decreasing.