The incidence of aortic valve prolapse and aortic regurgitation (AR) among Chinese with ventricular septal defect (VSD) has not been studied, and controversies still exist regarding optimal surgical treatment and timing of operation for this condition. A prospective study of 332 consecutive patients with VSD showed that aortic valve prolapse and AR occurred in 43 (11.9%) patients. Valve lesions occurred more commonly among patients with subpulmonic VSD (28.0%) than with subaortic VSD (8.8%) (P less than 0.005). A retrospective study of another 306 patients revealed that 37 (12.1%) had valve complications. Of the 80 patients with valve lesions, 60 were males and 20 were females. The youngest ages of prolapse and AR in subpulmonic VSD were 7 months and 3 years 8 months, respectively; those in subaortic VSD were 2 years and 3 years 6 months, respectively. Valve prolapse occurred mostly before the age of 6-10 years, leading progressively to AR. The coronary cusps prolapsed in subpulmonic VSD were limited to the right cusp; and those in subaortic VSD were the right cusp, noncoronary cusp, or both. The magnitude of left-to-right shunts was small and the pulmonary artery pressure was normal in the majority of patients. Seventy-two patients underwent open-heart closure of the VSD, with additional valvuloplasty in 15 and valve replacement in three patients. It is concluded that Chinese with VSD are prone to develop aortic valve complications. Surgical closure of the subpulmonic VSD may restore the prolapsed valve to normal. Closure of the subaortic VSD has little effect. Valvuloplasty in subaortic VSD may palliate AR, but in all probability cannot restore valve competency.