Abnormalities of calcium homeostasis are a recognized feature of end-stage renal disease. The treatment of choice is renal transplantation, but this does not always result in normalization of the biochemical profile. Persistent hypercalcaemia is well documented and our study was undertaken to investigate the status of the calcium regulating hormones in renal patients post-transplantation. Serum calcium, parathyroid hormone, 1,25-dihydroxyvitamin D (1,25(OH)2D) and osteocalcin concentrations were measured in post-transplant patients. Twenty per cent of the patients had subnormal 1,25(OH)2D concentrations while 55% had biochemical evidence of hyperparathyroidism but only 5% were hypercalcaemic. Time elapsed since transplantation was not correlated with any of the analytes investigated and there was no relationship between persistent impairment of renal function and abnormalities of calcium homeostasis.