Organizational culture (OC) has emerged as one of the foremost themes in management studies and organizational behavior over the past three decades. This research aims to measure the impact of OC on organizational citizenship behavior (OCB) in a sample of five-star hotels. It also examines the mediating role of affective commitment (AC) in the relationship between OC and OCB. For this purpose, online questionnaire was adopted with a random sample of employees in the investigated hotels. A number of 400 forms was distributed, among them 331 forms (83%) were completed and valid for analysis. The research hypotheses tested through multiple regressions analysis and the mediating effect was tested using Sobel z test. The results showed that OC positively affect OCB. Furthermore, AC partially mediates the relationship between OC and OCB. Based on the results it is recommended that hotel managers should pay special attention when choosing their employees specially who have OCB attributes in their personality because this will affect job outcomes.