The main objectives of this study are to: (i) measure hospital service quality by using analytic hierarchy process (AHP) and analytic network process (ANP) as a multicriteria decision making method to acquire the relationship and the level of the importance among service quality measurement (SERVQUAL) dimension; (ii) find perceived service quality with respect to different hospital classes (A, B and C) in Istanbul, Turkey; (iii) compare AHP- and ANP-based weighted SERVQUAL scales with the unweighted SERVQUAL scale for public hospital service quality in terms of different hospital classes (A-B and C). First, four hospitals are selected randomly for each class and then, a questionnaire based on the SERVQUAL model is conducted for each class to measure perceived service quality with respect to five major criteria, namely tangible, reliability, responsiveness, assurance and empathy, from patients' viewpoints at hospitals. Next, the second questionnaire based on ANP is developed to evaluate the importance of criteria and construct the relations among the criteria. The study sample contains 281 outpatients totally. Three important findings are obtained in this study. First, there is a significant difference among different hospital classes regarding the perceived service quality. Second, according to the patients, the most important service quality dimensions are empathy, the knowledge of employees, sympathetic and reassuring employees, services provided at the time promised to do so, and safe feeling of patients in interactions with hospital employees. Thirdly, the, perceived service quality through the AHP- and ANP-based SERVQUAL scale is higher than that with the unweighted SERVQUAL scale.