Patient-reported outcomes (PROs) are increasingly used in randomized controlled trials (RCTs) to foster patient-centered healthcare. The aim of this investigation was to assess the completeness of reporting of PROs in RCTs pertaining to cystic fibrosis (CF).We searched MEDLINE, Embase, and Cochrane Central Register of Controlled Trials for RCTs concerning CF that included PROs as a primary or secondary outcome. The RCTs were assessed by 2 independent investigators using an adaptation of the Consolidated Standards of Reporting Trials for Patient-Reported Outcomes (CONSORT-PRO) and the Cochrane Risk of Bias (RoB) 2.0 assessment. We calculated the mean completion percentage of adherence to the CONSORT-PRO adaptation and used bivariate regression models to evaluate for associations with particular trial characteristics.Our systematic search returned 2302 potential studies. Fifty-nine eligible RCTs were included after full-text screening. The RCT mean completeness of reporting was 38.38% (SD = 12.74). We found the following associations between trial characteristics and completeness of PRO reporting: (1) significantly higher reporting completeness for RCTs published in journals requiring adherence to the CONSORT guideline (p-value = 0.049), (2) improved reporting completeness in studies with 'some concerns' of RoB versus 'high' RoB (p-value = 0.042), and (3) significantly better reporting completeness when the PRO is the primary outcome of a RCT (p-value = 0.006).Inadequate PRO reporting exists within RCTs focused on CF. Given that CF has substantial effects on quality of life, PROs are imperative to understand patients' experiences. We believe greater adherence to CONSORT-PRO will promote the standardization of PRO reporting and will facilitate comprehension of PROs by stakeholders, patients, and clinicians.