Results Baseline characteristics were similar across all arms, with overall mean6SD 25(OH)D levels of 21.966.9 ng/ml. At 12 weeks, vitamin D sufficiency (25[OH]D .32 ng/ml) was achieved in 91% (weekly), 66% (monthly), and 35% (placebo) (P,0.001). Mean 25(OH)D was significantly higher in both the weekly (49.862.3 ng/ml; P,0.001) and monthly (38.362.4 ng/ml; P=0.001) arms compared with placebo (27.462.3 ng/ml). Calcium, phosphate, parathyroid hormone levels, and active vitamin D treatment did not differ between groups. All-cause and cause-specific hospitalizations and adverse events were similar between groups during the intervention period. Lower all-cause mortality among ergocalciferol-treated participants was not statistically significant (hazard ratio, 0.28; 95% confidence interval, 0.07 to 1.19).Conclusions Oral ergocalciferol can increase 25(OH)D levels in incident hemodialysis patients without significant alterations in blood calcium, phosphate, or parathyroid hormone during a 12-week period.