Preliminary studies have shown a benefit of sodium bicarbonate infusion in decreasing the risk of contrast induced nephropathy with coronary angiography. The investigators plan to randomize 478 patients (with serum creatinine 1.5 mg/dl or greater) undergoing coronary angiography to intravenous isotonic saline or intravenous isotonic sodium bicarbonate beginning one hour before the procedure and for four hours after. The primary endpoint is the development of contrast nephropathy within 48-72 hours after the procedure. Patients with an ejection fraction <30%, overt CHF, hypokalemia and alkalemia will be excluded.