Twelve patients who had undergone diaphragmatic plication with the diagnosis of congenital diaphragmatic eventration between 1975 to 1989 were evaluated for the long-term results of plication. Assessment of the long-term functions of the plicated diaphragms 1.5 to 11 years postoperatively was achieved by fluoroscopic, ultrasonographic, and spirometric studies. The absence of paradoxical motion with normal localization of the diaphragms in all patients, and satisfactory motions of diaphragms in 9 patients were documented by fluoroscopy. Measurements of diaphragmatic thicknesses showed that plicated diaphragms of all patients maintained their growths in proportion to the contralateral sides. Additionally, normal values of pulmonary function tests in five of six patients of suitable age for spirometry were obtained. All the clinical studies demonstrated that diaphragmatic plication did not interfere with further development of diaphragms, and late functional results of the plication were acceptable. This supports the choice of surgery in the treatment of diaphragmatic eventration.