OBJECTIVE: To assess whether flexible nasoendoscopy can be used to visualize all parts of the olfactory cleft (OC) without morbidity.STUDY DESIGN: Single-center, prospective, observational study.SETTING: French tertiary referral center.SUBJECTS AND METHODS: 100 consecutive patients were divided in 2 groups of 50. Group 1 underwent nasal fibroscopy without vasoconstriction or local anesthesia with an endosheath- protected endoscope. Group 2 was examined by a fiberscope without an endosheath after application of naphazoline Xylocaine. Each OC was divided in 16 items recorded as visualized or not. Four scores were compared between both groups: out of 16 (1 side), out of 32 (both sides), out of 12 concerning only the narrowest and highest bilateral spaces, and out of 4 to divide these specific areas in anterior, middle, and posterior parts. Length of procedure, pain, epistaxis, blood mark on the endosheath, sneezing, rhinorrhea, and causes of failure were recorded.RESULTS: There was no significant difference between both groups concerning score out of 16 or 32. The visibility of the narrower and higher spaces was better in group 2: scores out of 12 were significantly different between the groups (P = .025), as were scores out of 4 for the anterior and middle parts of the OC (P = .02 and .01 respectively). Morbidity was low without differences between the groups. Deviated nasal septum was the only cause of failure and increased the patients' pain during the examination (P = .045).CONCLUSION: Nasal fibroscopy could be used to explore the different portions of the OC efficiently and with low morbidity.