Between June 1972 and August 1989, we operated on 45 patients with fixed subaortic stenosis. Discrete membranous stenosis was present in 28 patients and tunnel stenosis, in 13. Four patients had subvalvar stenosis complicating double-outlet right ventricle. There were 33 male and 12 female patients. Mean age at operation was 7.1 +/- 4.3 years (range, 6 months to 21 years). Local resection of the fibrous membrane was performed in 26 patients. Local resection was combined with myectomy in 18 patients. Aortoventriculoplasty (modified Konno procedure) was required at operation in 3 patients. There were three perioperative deaths at initial operation and two deaths at the time of reoperation. Follow-up ranges from 1 month to 17 years (average follow-up, 47.0 months). Reoperation for recurrent obstruction has been required in 12 patients (27%), and 3 patients have required a second reoperation. Mild to moderate aortic regurgitation was present in 17 patients. Subaortic stenosis is a spectrum of anatomical derangements ranging from a discrete fibrous membrane to a long, tortuous fibrous tunnel with aortic annulus hypoplasia. Successful removal of a discrete fibrous membrane can be followed later by recurrent stenosis necessitating myectomy or aortoventriculoplasty. Correction of subvalvar aortic stenosis can be followed by recurrent stenosis necessitating reoperation as long as 17 years after the initial procedure.