CAPD is considered a risk factor for low turnover bone disease. This was previously attributed to aluminum accumulation. We evaluated by biochemical and histomorphometric parameters (including double tetracycline labelling), 26 patients maintained on CAPD for 12-14 months. Three (11.5%) showed mild hyperparathyroidism, 5 (19.2%) osteitis fibrosa, 3 (11.5%) mixed forms, 4 (15%) osteomalacia and 11 (42.3%) adynamic bone disease. Only one patient with diabetes mellitus showed an aluminum stained bone surface > 10%. Intact PTH serum levels were lower in LTBD (133.2 +/- 128 vs 468.2 +/- 451 pg/ml; p < 0.05). We also evaluated prospectively 11 patients who underwent a bone biopsy at start of dialysis and after 12 months of CAPD treatment. Bone biopsies pre CAPD demonstrated normal-high bone turnover disease in 8/11 (72.7%) and low turnover bone disease in 3/11 (27%). In the follow-up biopsies, 2 patients showed osteitis fibrosa and other two mild forms. Low turnover bone disease was found in 7 patients (3 osteomalacia and 4 adynamic bone disease). We conclude that the predominant bone lesion in our CAPD patients is low turnover bone disease, predominantly adynamic forms, and aluminum does not seem to play a role on its genesis. Low intact PTH serum levels may be a predictor of low turnover bone disease.