A Study of the Comparable Efficacy and Safety of Pulmozyme (Dornase Alfa) Delivered by the eRapid Nebulizer System in Patients With Cystic Fibrosis

Inclusion Criteria: * Male and female patients, \>/= 6 years of age * Confirmed diagnosis of cystic fibrosis (CF) * Receiving Pulmozyme once daily chronically for treatment of CF for at least 6 months prior to screening * Percent predicted FEV1 \>/= 40% at screening based on the Wang (males \< 18 years, females \< 16 years) or Hankinson (males \>/= 18 years, females \>/= 16 years) standardized equations * Able to reproducibly perform spirometry testing and comply with study assessments Exclusion Criteria: * An acute respiratory infection or pulmonary exacerbation within 4 weeks prior to randomization * Initiation of any new chronic therapy (e.g. inhaled corticosteroids, inhaled oral antibiotics, high-dose ibuprofen, hypertonic saline, ivacaftor) for respiratory disease within 4 weeks prior to randomization * Changes in chest physiotherapy schedule within 4 weeks prior to randomization * Hospitalization within 4 weeks prior to randomization * Planned hospitalization during the 6-week study * History of organ transplantation * Participation in an investigational drug or device study within 30 day prior to screening