This paper identifies the results of a questionnaire designed to measure service quality in spa hotels in the Republic of Serbia. Service quality was measured with a model based on the original SERVQUAL model. Due to the fact that many previous research papers have shown that SERVQUAL is insufficient to identify and measure all determinants of service quality in hospitality, the original SERVQUAL model has been slightly changed. Namely, this modified version of SERVQUAL was adjusted to measure a large number of tangible and intangible elements of the service quality in spa hotels. Based on the research results, seven dimensions of the service quality were identified: assurance, food and benefits, empathy, entertainment, recreation facilities and wellness, responsiveness and reliability. After applying the modified SERV-QUAL model, an Importance -Performance Analysis (IPA) was performed. By using an Importance -Performance Analysis (IPA), this paper examines the efficiency of hotel resources allocation and the possibility of designing management strategies to improve the quality of hotel service.