Forty-eight patients with predominant aortic stenosis underwent His bundle electrography (HBE) at the time of diagnostic catheterization. Patients were divided into four groups based upon severity of calcification of the aortic valve fluoroscopically as judged independently by three angiographers. Of 48 patients, three had no calcification, 11 had mild, 18 had moderate, and 16 had severe aortic valve calcification. No correlation was found between HV interval and severity of aortic valve calcification. Significant correlation was found between HV interval prolongation and aortic valve area (p less than 0.02), history of congestive heart failure (p less than 0.02), and increasing left ventricular end-diastolic pressure (p less than 0.05). Left ventricular ejection fraction less than 45% had greater likelihood of HV interval prolongation (p less than 0.01). No correlation was established between HV interval and age, aortic valve gradient, left ventricular peak systolic pressure, syncope, and coronary artery disease. Aortic valve area was the most significant independent predictor of HV prolongation, with history of congestive heart failure second. We conclude that HV interval prolongation in aortic stenosis with calcified valves is best predicted by evidence of declining left ventricular function rather than severity of aortic valve calcification.