This was a Phase IV, multicenter, randomized, double-blind, placebo-controlled trial designed to evaluate the effect of Pulmozyme on pulmonary function, health-related quality of life (HRQOL), and respiratory symptoms in 3- to 5-year-old children with cystic fibrosis (CF). Approximately 40 patients were planned to be enrolled in this study. However, only 3 patients were eligible for random allocation and received treatment: 1 patient in the Pulmozyme group and 2 patients in the placebo group. All 3 patients completed the study assessments but did not have usable pulmonary function test (PFT) data.