Abstract Background: Despite increasing knowledge of the uraemic syndrome,both morbidity and mortality remain unacceptably high in patients with chronic kidney disease. Study investigates the differences between conventional hemodialysis and hemodiafiltration in the context of chronic kidney disease metabolic bone disease findings, serum calcium (sCa), phosphate (sPO4) and intact parathyroid hormone (PTHint) concentrations. Patients and methods: This prospective cross over study was approved by Almaadi hospital committee and included 95patients with CKD5 on regular hemodialysis for at least 6months.Patients were divided into two groups:Group A:60patients scheduled 6months conventional high flux(hf-HD)(Period1) followed by 6months of post-dilutional –HDF (Period2). Group B:(controls)included 35patients were kept on conventional hf-HD for12months.(Period3)for 1st 6months and(Period4) for 2nd 6months.The main variables evaluated at the start as well as at the end of each period were sCa, sPO4 and PTH int. Results: There was highly significant statistical decrease in Phosphorus level in period2 compared to other groups after 2nd to 6th month and average of overall (p<0.001).A significant statistical decrease was found in Parathormone level and CRP in period2 compared to other groups after 1month to 6th month and average of overall (p<0.05).There was significant statistical decrease in Albumin level in period2 compared to other groups after 2nd to 6th month and average of overall (p<0.05).There was a significant statistical increase in kt/v in period2 compared to other groups after 1st to 6th month and average of overall (p<0.05). Conclusion: The switch over from conventional Hf-HD to Ol-HDF results in a significant reduction of both PO4 and PTH concentrations, no significant changes in Ca concentrations.