Background and objectives Sodium bicarbonate has been proposed for protection of the kidney from contrastinduced AKI (CIAKI). However, the effects of bicarbonate on long-term important clinical outcomes are uncertain.Design, setting, participants, & measurements In a prospective, double-blind, multicenter randomized clinical trial, 391 patients with an eGFR,45 ml/min per 1.73 m 2 undergoing elective coronary or peripheral angiography were randomized to an infusion with a high dose of isotonic sodium bicarbonate (target 2.0 mEq/kg) or a similar molar amount of isotonic sodium chloride. The primary outcome was a composite of mortality, dialysis, or a sustained 20% reduction in eGFR at 6 months.Results There were 391 patients enrolled between March 2010 and May 2012. The incidence of the primary outcome was 14.9% in the bicarbonate group and 16.3% in the control group in the intention-to-treat population (P=0.78). There was also no difference in the incidence of CIAKI between the treatment groups (14.5% versus 12.1%, respectively; P=0.20). CIAKI was associated with a higher incidence of sustained loss of kidney function at 6 months compared with those without CIAKI (21.2% versus 7.7%, respectively; P=0.06).Conclusions High-dose sodium bicarbonate infusion in patients with eGFR,45 ml/min per 1.73 m 2 undergoing angiography did not demonstrate a difference in incidence of the composite of death, dialysis, or sustained 6-month reduction in eGFR or CIAKI compared with sodium chloride.