Background: Chronic pulmonary infection is the leading cause of mortality and morbidity in patients with cystic fibrosis (CF). The most common pathogens isolated in CF are Staphylococcus aureus and Pseudomonas aeruginosa (P. aeruginosa). Chronic infection of P. aeruginosa and MRSA are associated with worse survival and antibiotic eradication treatment is recommended for both. This study evaluates the efficacy of intravenous (IV) vs. non-IV antibiotics in the eradication of P. aeruginosa and MRSA. Methods: This was a single-center retrospective study at a large CF center. All respiratory specimen cultures of 309 CF patients and eradication regimens between 2015-2019 were reviewed. The primary analysis was the comparison of the percentage of successful eradication after receiving IV and non-IV eradication regimens. Demographic and clinical risk factors for eradication failure were also analyzed. Results: 102 patients with P. aeruginosa isolations and 48 patients with MRSA were analyzed. At one year, 21.6% in P. aeruginosa group and 35.4% in MRSA group were successfully eradicated. There was not any statistically significant difference between IV vs. non-IV antibiotic regimens on eradication in either group. Additionally, none of the clinical risk factors was significantly associated with eradication failure in P. aeruginosa and MRSA groups. Conclusion: In the eradication of P. aeruginosa and MRSA, IV and non-IV treatment regimens did not show any superiority to one another. Non-parenteral eradication could be a better option in eradication considering the cost-effectiveness and the treatment burden of IV treatments due to hospitalization and the need for IV access.