Purpose: To assess awareness of, opinion about and adherence to evidence-based guidelines on chronic rhinosinusitis among Dutch Otolaryngologists. Methods: We assessed implementation of two guidelines, one Dutch and one European, that are both intended for diagnosis and treatment of patients with chronic rhinosinusitis. We invited 485 Otolaryngologists to fill out a questionnaire and report on their opinion on and adherence to the guidelines. The adherence was further tested by 4 clinical case scenarios, derived from guideline recommendations. Results: 166 (34%) completed the questionnaire. 99% of the respondents was aware of one or both guidelines. Most respondents (90%) consider the guidelines as directing or supportive for their clinical practice based on the clinical case scenarios, between 62 and 99% of the respondents act according to guidelines. Concerning diagnosis, CT-imaging is performed more and allergy testing less than recommended. Where multiple treatment options are recommended, the responses are more heterogeneous as a result of this. Nonetheless, high recommended treatment was chosen more often. Otolaryngologists were reluctant in surgical treatment as a first option, which is according to the guidelines. Conclusions: Overall, both the EPOS and CBO guideline are well known among Dutch Otolaryngologists and 90% indicates that the guideline is important in their daily practice. Adherence to the guidelines is sufficient to high. If multiple treatment or diagnostic options are recommended this leads to a more heterogeneous response pattern. Recommendations with a high grade of recommendation were followed up most often.