In order to evaluate the influence of sex on bone metabolism in patients on regular dialytic treatment, 82 patients (51 males and 31 females) were studied. All the women were amenorreic and none of them took estrogens. Women showed radiological features of hyperparathyroidism more frequently than men and, in addition, higher bone GLA protein and lower calcitonin serum levels. In both sexes a significant positive correlation was observed between PTH and BGP, but the slope was higher in females, even though not significant. These results suggest that the uremic females show an increased skeletal sensitivity to PTH, probably due to the lack of protective effect of estrogens.