Objectives: We sought to objectively assess our outcomes after laparoscopic diaphragmatic plication for symptomatic hemidiaphragmatic paralysis or eventration using a respiratory quality-of-life questionnaire and pulmonary function tests. Methods: We performed a retrospective review of all symptomatic patients with hemidiaphragmatic paralysis or eventration who underwent laparoscopic diaphragmatic plication from March 1, 2005, through August 31, 2008. Patients with primary neuromuscular disorders were excluded from our analysis. We collected St George's Respiratory Questionnaire scores (a respiratory quality-of-life questionnaire) and pulmonary function test results preoperatively and at 1 month and 1 year postoperatively. A 2-sided significance level of .05 was used for all statistical testing. Results: During the study period, 25 patients underwent laparoscopic diaphragmatic plication (9 right-sided and 16 left-sided plications); 1 patient required conversion to a thoracotomy. St George's Respiratory Questionnaire total scores (59.3 ± 26.8) improved by more than 20 points on average (a reduction of ≥4 points after an intervention is considered a clinically significant improvement). This improvement was statistically significant at 1 month (36.6 ± 15.9, P = .001) and maintained significance at 1 year (30.8 ± 18.8, P = .009). Similarly, percent predicted maximum forced inspiratory flow (93.2% ± 34.1%) was significantly improved 1 month after plication (113.9% ± 31.8%, P = .01) and maintained significance at 1 year (111.5% ± 30.9%, P = .02). Conclusions: Our objective evaluation of laparoscopic diaphragmatic plication for hemidiaphragmatic paralysis or eventration demonstrated significant short-term and midterm improvements in respiratory quality of life and pulmonary function test results. This approach represents a potential paradigm shift in the surgical management of hemidiaphragmatic paralysis or eventration.