In 48 pts on maintenance haemodialysis 6-140 months (mean 47.8 months) radiological, biochemical and densitometrical signs of renal osteodystrophy were evaluated. Bone densitometry, determination of Bone Mineral Content (BMC) by singl photon absorptiometry was performed. The following biochemical parameters included: serum calcium, serum phosphate, serum alkaline phosphatase and serum parathormon (RIA for C-terminal fragment). All pts were divided in three groups. The first group included 13 pts and had no radiological signs of renal osteodystrophy, the second included 24 pts and had radiological signs of osteitis fibrosa cystica, and the third included 11 pts who had radiological signs of osteomalacia. The mean values of duration on maintenance haemodialysis, biochemical parameters and BMC in these groups were compared. It was found that pts with radiological signs of osteitis fibrosa cystica had the highest levels of serum calcium, serum phosphate and serum parathormon, moderately elevated serum alkaline phosphatase and moderately decreased BMC. However, pts with radiological signs of osteomalacia had the longest duration of maintenance haemodialysis, the highest level of serum alkaline phosphatase and the lowest levels of serum calcium, serum phosphate, as the lowest BMC, but mild elevated serum parathormon. Our results showed good correlations between biochemical, radoilogical and densitometrical signs of second hyperparathyroidism, but these correlations are less valuable for osteomalacia. Bone densitometry in common with biochemical parameters and diagnostic radiology may contribute to better differentiation of the type of renal osteodystrophy.