OBJECTIVE The aim of this retrospective study was to assess parathyroid function after renal transplantation in patients with good renal function (creatinine < 133 mumol/l). METHODS Of 1,628 patients on whom we performed renal transplantation, 210 have stable good renal function as defined above. Total calcium (Ca), creatinine, albumin and parathyroid hormone (PTH) values were obtained from patient records at varying intervals after transplantation, and in 91/210 patients pre-transplant values were available. Patients who had undergone parathyroidectomy before the transplant were excluded from the study. Follow-up ranged from 6 months to 24 years. RESULTS These 210 patients were divided into 4 groups according to PTH and Ca levels. Group 1 consisted of 118 patients (56%) with normal Ca and PTH levels and group 2 of 69 patients (33%) with normal Ca but persistently high PTH levels, of whom 25 persistently have Ca levels in the high normal range. The reason for the inappropriate PTH levels is not obvious. In group 3 there were 18 patients (8%) with high Ca and PTH levels. They have disease requiring parathyroidectomy. Group 4 comprised 5 patients (3%) with low Ca and high PTH levels. In the 91 patients for whom pre-transplant PTH values were available, 16/46 patients with tertiary hyperparathyroidism (3 degrees HPT) have normalised after transplant, 12/46 patients have ongoing 3 degrees HPT post transplant, while 4/45 patients with less severe disease (secondary HPT) have developed 3 degrees HPT (P < 0.059). CONCLUSIONS In 56% of patients with good renal function after transplant parathyroid function is normal. Thirty-three per cent have high PTH levels with normal Ca, but 36% of these are in the high normal range. Eight per cent have persistent 3 degrees HPT. Post-transplant parathyroid dysfunction correlates with the severity of pre-transplant disease.