Preoperative localisation procedures in primary hyperparathyroidism have been associated with advantages like decreased operative dissection, shorter operating time and in some series, lower morbidity and mortality. However, successful identification of parathyroid glands exceeding 90% is achievable at surgery without preoperative localisation studies. Sixty-nine patients who underwent parathyroidectomy at the Department of Surgery, Singapore General Hospital, between March 1990 and July 1996 were analysed to determine the role of preoperative localisation techniques. Preoperative localisation of parathyroid glands consisted of computed tomographic (CT) scan in 66.7% of patients, technetium99 sestamibi scan in 23.2%, ultrasound in 15.9% and angiographic localisation in 4.3% of the patients. In the 28 end stage renal failure patients who were operated for progressive renal osteodystrophy, 6 had preceding renal transplants. The success of identifying parathyroid glands at operation in these 28 patients was independent of CT scan findings. CT scan was correct in only 6% of patients while surgical exploration had a success rate of 100%. Of the 41 patients with primary hyperparathyroidism, the success of CT scan in identifying enlarged parathyroid glands was 41.4% compared to 91.6% via surgical exploration. Furthermore, CT scan was not able to discriminate between superior and inferior parathyroid glands. Preoperative Tc-99m sestamibi scan and ultrasound correctly localised pathologic parathyroid gland in 40% and 18.2% of the patients, respectively. Therefore, the use of preoperative imaging to localise parathyroid glands before the intended exploration was found not to be useful in our series.