Organizations today are becoming customer oriented due to increased competition. The goal of services providers is to develop services which attract and keep customers who are satisfied, loyal and speak well of the organization. The nature of services makes the evaluation of service quality subject of many researches. But evaluating service quality of airlines was not much studied. The aim of this research is to find out the dimensions of service quality for airlines and using them to evaluate the service quality of Pakistan International Airlines (PIA). Further the research finds the relationship between the service quality provided by PIA and their customer satisfaction. The data collected through a questionnaire was analyzed via factor analysis, regression analysis, correlation analysis and hypotheses test. The results of the survey suggest that there is a direct relationship between all the service quality dimensions (Reliability, Comfort, Personal attention, Physical features) and the service quality. A strong and significant relationship was also found between the service quality and customer satisfaction.