Background /Aim:Vitamin D deficiency is associated with a multitude of clinical consequences; Treatment of 25-hydroxyvitamin D (25-D) deficiency has been associated with positive outcomes. The aim of this work is to examine the impact of Ergocalciferol supplementation on markers of mineral metabolism and anemia in a cohort of 25-D deficient hemodialysis patients.Method:35 HD patients were recruited and serum 25(OH) D levels were specifically measured by RadioImmune Assay with Ergocalciferol supplementation.Results:Plasma levels of 25(OH)D was significantly low in the study (10 (28.6%) had 25(OH) D insufficiency (16–30 ng/ml), 18 (51.4%) had 25(OH) D deficiency (more than 5–15 ng/ml), and 7 (20%) had severe 25(OH)D deficiency with a level ≤ 5 ng/ml. (table 1).At 6 month follow up participants who had been compliant (n = 30) with the ergocalciferol regimen had a significant increase in serum 25(OH) D levels (12.29 ± 6.0 to 38.65 ± 12.63 ng/ml, p < 0.000) while those that were not compliant (n = 5) had no significant change (7.94 ± 2.86 to 12.08 ± 4.25 ng/ml, p = 0.118) (table 5). The compliant group also had a significant decrease in serum phosphorus (5.14 + 1.316 vs. 4.16 + 1.554 mg/dl, p = 0.000) and in Parathyroid Hormone level (246.92 + 175.445 vs. 203.23 + 143.935 mg/dl, p = 0.002) but there was no significance in the calcium level. There was a significant negative correlation between the compliant group with both Phosphorous and Parathyroid hormone levels (r = -0.423 and -0.454 respectively), (P < 0.05). (fig1,2)Conclusion:Serum 25(OH)D levels were associated with Parathoromon status and parameters of bone and mineral metabolism in maintenance hemodialysis patients, correction of 25(OH)D levels seem to play a significant role in lowering PTH level of HD patients, however it is difficult to use it as clinical marker due to cost of its measurement (Almost 100 L.E/person).