UNLABELLED: The aim of the present investigation was to examine the influence of age, sex and body weight on osseous changes in pre-dialysis patients with chronic renal failure (CRF). 87 patients (44 males and 43 females) aged 18-60 years with CRF were studied. The levels of serum creatinine, total and ionized calcium, phosphorus, alkaline phosphatase, intact parathormone and serum osteocalcine were followed up. Body weight is presented as BMI. 47 of the patients were subjected to double X-ray absorptiometry of lumbar vertebra (Lunar) and 40 patients were examined by computed tomography osteometry. RESULTS: No reliable differences in the levels of biochemical parameters in male and female patients with the same degree of CRF were established. A tendency towards an increase in the level of intact parathormone and serum osteocalcine in women with both initial and advanced CRF was recorded. The BMI in patients with advanced CRF was lower as compared to those with initial CRF. Different stages of osseous changes were observed in 29 males (74.35%) and in 25 females (60.97%). A tendency for a higher frequency and severity of osseous changes in men aged up to 40 years was observed. After this age males and females were equally affected. A high positive correlation (r = 0.50) between BMI and the percentage of the normal Bone Mineral Density/Bone Mineral Content in females with CRF stage II and III was noticed. CONCLUSIONS: No significant difference in the frequency and severity of osseous changes in male and female uremic patients was observed. Bone changes were more frequent and pronounced in males up to 40 years of age, while this tendency reversed after the menopause. The higher body weight was beneficial for the osseous changes only in females with advanced CRF, while in all other patients no correlation with densitometric parameters was noticed.