Abstract Objectives : The Reflux Finding Score for Infants (RFS-I) was developed to assess signs of laryngopharyngeal reflux (LPR) in infants. With flexible laryngoscopy, moderate inter- and highly variable intraobserver reliability was found. We hypothesized that the use of rigid laryngoscopy would increase reliability and therefore evaluated reliability of the RFS-I for flexible versus rigid laryngoscopy in infants. Design We established a set of videos of consecutively performed flexible and rigid laryngoscopies in infants. The RFS-I was scored twice by 4 otorhinolaryngologists, 2 otorhinolaryngology fellows, and 2 inexperienced observers. Cohen's and Fleiss' kappa ( k ) were calculated for categorical data and the intraclass correlation coefficient (ICC) was calculated for ordinal data. Results The study set consisted of laryngoscopic videos of 30 infants (median age 7.5 (0-19.8) months). Overall interobserver reliability of the RFS-I was moderate for both flexible (ICC=0.60, 95%CI 0.44-0.76) and rigid (ICC=0.42, 95%CI 0.26-0.62) laryngoscopy. There were no significant differences in reliability of overall RFS-I scores and individual RFS-I items for flexible versus rigid laryngoscopy. Intraobserver reliability of the total RFS-I score ranged from fair to excellent for both flexible (ICC=0.33-0.93) and rigid (ICC=0.39-0.86) laryngoscopy. Comparing RFS-I results for flexible versus rigid laryngoscopy per observer, reliability ranged from no to substantial ( k= -0.16-0.63, mean k =0.22), with an observed agreement of 0.08-0.35. Conclusion Reliability of the RFS-I was moderate and did not differ between flexible and rigid laryngoscopy. The RFS-I is not suitable to detect signs of LPR in infants or to guide treatment, neither with flexible, nor with rigid laryngoscopy.