From April 1973 through March 1978, 34 patients with univentricular heart and outlet chamber underwent repair by septation of the ventricle. Three had normally related great arteries in which the pulmonary artery arose from the outlet chamber. Six patients had an anterior aorta arising from an anterior or right-sided outlet chamber and 25 patients had an anterior aorta arising from a left-sided outlet chamber. The ages ranged from 3 to 36 years. Fourteen patients had had previous palliative operations. There were 13 hospital deaths and four late deaths. Four patients have a fair result and the remaining 13 patients are in good health clinically. For the more favorable types of univentricular heart with outlet chamber on the left and natural pulmonary stenosis, the risk of corrective operation is less than 20 percent. The improved clinical course of those patients who have survived and done well gives encouragement that continued refinements in the operative repair of univentricular heart should ultimately provide many of these patients with a good result.