Purpose: Primary hyperparathyroidism (PHPT) commonly causes neuromuscular dysfunction such as weakness and fatigue which can substantially impair daily activity. Although many patients report subjective improvement after parathyroidectomy (PTX), objective data supporting improvements in neuromuscular performance after successful parathyroid surgery are limited. We sought to assess objective changes in muscle endurance and functional capacity after PTX for PHPT. Methodology: A prospective cohort study was conducted in patients with PHPT undergoing PTX. Muscle endurance and functional capacity were assessed using the 30-second sit-to-stand (STS) test and maximum dominant hand grip strength (HGS) measurement preoperatively and at 3 months postoperatively and compared via paired t-test. Change in STS and HGS was also compared between-groups in those with preoperative normocalcemia (<2.6mmol/L) and hypercalcemia (≥2.6mmol/L) using Mann-Whitney U tests. Results: 76 patients with PHPT underwent PTX. 75.3% were female. Mean preoperative serum corrected Ca was 2.61mmol/L and median age was 66. Focused PTX was performed in 51% of cases and the median adenoma weight was 490mg. Median STS improved from 12 repetitions preoperatively to 14 repetitions at 3 months postoperatively (p<0.001). Mean maximum dominant HGS improved from 24.1kg to 25.6kg at 3 months postoperatively (p<0.001). There was no significant difference in change in STS or HGS between patients with pre-operative normocalcemia (corrected calcium <2.6 mmol/L) and those with hypercalcemia (corrected calcium ≥2.6 mmol/L) (STS p=0.26, HGS p=0.87). Conclusions: Parathyroidectomy for PHPT is associated with significant improvement in STS and HGS. Improvement was similar regardless of preoperative calcium status. This suggests that accompanied with subjective feelings of improved strength and energy is an objective improvement in proximal muscle endurance, strength, and functional capacity following parathyroidectomy.