Some more controversial points in the interpretation of metabolic bone disease in end-stage renal failure are dealt with in this communication. The pattern of clinical signs changes with duration of dialysis and is strikingly different in dialysed children as compared with adults. Haemodialysed women bear children with apparently no skeletal disease. Animal experiments failed to show defective mineralisation in the fetal skeleton of the offsprings of uraemic pregnant rats, possibly pointing to a compensatory role of the fetal kidney in the metabolism of vitamin D. Some fallacies in the interpretation of X-ray signs in azotaemic patients are stressed: replacement of lamellar bone by woven bone and especially replacement of primary spongiosa underneath the growth plate by fibrous tissue (roentgenologically misinterpreted as rickets) are mentioned. The discrepant behaviour of cancellous vs. cortical bone is analysed.