An open patch-graft technique for correction of pulmonic stenosis was performed in four dogs. A synthetic patch-graft was presutured to a partial-thickness incision in the right ventricular outflow tract and to the pulmonary artery along its cranial border. The pulmonary artery and right ventricle were incised during venous inflow occlusion, and dysplastic pulmonic valve leaflets were excised. The arteriotomy was closed by suturing the caudal margin of the incision to the patch-graft. The entire procedure was performed during mild hypothermia (30°-32° C). The mean circulatory arrest time was 5.5 ± 0.2 minutes. The mean systolic pressure gradient across the pulmonic valve before surgery was 121 ±29 mm Hg; after surgery it was 9 ± 2 mm Hg.