This is the first known attempt to quantitate periosteal resorption (PR) and perisoteal neostosis (PN) by a semi-automatic image analysis system (Zeiss MOP-3). The normal ranges and errors for PR were found to be similar to those of a previous study using a measuring magnifier. The findings in chronic renal failure patients showed that MOP-3 measurements were actually diagnostically slightly less sensitive than the results by a simple grading method. Comparison with plasma-immunoreactive parathyroid hormone (iPTH) concentrations showed that while the latter had a higher sensitivity for detection of hyperparathyroidism, the radiologic parameters nevertheless showed abnormal PR in 12% of the observations where iPTH was normal. Both PR and PN correlated significantly with iPTH (r = 0.55 and 0.30 respectively, P less than 0.01).