The topicality of customer engagement into value creation as a marketing research object has especially grown in the context of current value co-creation studies. The current exploration shows that most works on the topic of customer engagement into value creation have been performed in the case of services. Their analysis reveals that up till now no complex research has been done that would analyse reasons for engagement into value creation of customers of services and all possible intermediate variables of relations between customer engagement into value creation and loyalty. The aim of this article is to substantiate the integrated approach towards customer engagement into value creation identifying its determining factors and relations with loyalty in the case of health care services. The compiled theoretical framework reflects the integrated approach towards service customer engagement into value creation and encompasses two groups of relations between the research constructs. The results of the empirical research show that patients' engagement into value creation is strongly influenced by communication of a clinic's doctors, and the other three factors have an average influence. It has been revealed that the influence of patients' engagement into value creation on attitude loyalty is stronger not in the case of direct impact of patients' engagement into value creation on loyalty but through intermediate variables. This is based on the research results, which confirm the influence of patients' engagement into value creation on their satisfaction, trust, and relationship strength of a clinic's doctors. All the mentioned variables influence patients' attitude loyalty, and the strongest influence is identified in the case of trust. The influence of patient's engagement into value creation on behaviour loyalty has not been identified.