Parathyroid hormone (PTH) increases bone turnover and may thus increase fracture risk. As PTH secretion is increased in primary hyperparathyroidism, surgical cure may prevent fractures. We studied fracture risk before and after diagnosis in patients treated surgically and conservatively for primary hyperparathyroidism. All 1201 patients with newly diagnosed primary hyperparathyroidism (PHPT) between 1982 and 1996 in Denmark were identified through the Danish Hospital Discharge Register. Each patient was compared with three age- and gender-matched controls randomly drawn from the background population. Those who were treated surgically ( n = 841; mean age 58.6 +/- 14.6 years) were significantly younger than those who were not ( n = 360; 65.5 +/- 16.8 years; 2 p < 0.01); they had higher plasma ionized calcium (1.58 +/- 0.16 vs. 1.50 +/- 0.10 mmol/L; 2 p = 0.03) and tended to have lower lumbar spine bone mineral Z-scores (-0.72 +/- 1.35 vs. 0.05 +/- 1.05; 2 p = 0.06). Before diagnosis, fracture risk was elevated in both those who subsequently underwent surgery [incidence rate ratio (IRR) 1.45, 95% CI 1.05-1.99] and in those who did not (IRR 1.59, 95% CI 1.10-2.29). After diagnosis, no difference in fracture risk was present between surgically and nonsurgically treated patients. The risk of death was significantly lower in the operated patients than in those who did not have surgery (RR 0.58, 95% CI 0.47-0.73). No differences in fracture risk could be demonstrated between those who had and those who did not have surgery, taking age, gender, and previous fractures into account.