Objectives: In this study, we aimed to evaluate the treatment adherence, self-efficacy levels of adult patients using multiple drugs and the effects of individual factors affecting adherence. Materials and Methods: Methods: A 35-year-old or older patients who has been diagnosed with chronic disease who has been using more than one medication for the last 2 months were included in the study. A questionnaire prepared by the researchers to determine sociodemographic characteristics, disease status and drug types, a Short Form of Self-Efficacy Scale for Adherence/Adaptation to Medical Treatment and Modifiye Morisky Scale were applied to the patients. Results: Of the participants, 39.6% (n = 109) were male, 60.4% (n = 166) were female and the mean age was 67.42 ± 11.5 years. While 53.8% of patients said they were using their medication regularly, 44.7% were unable to use their medication regularly due to forgetfulness. The mean score of the Self-Efficacy Scale for Adherence/Adaptation to Medical Treatment was 33.65 ± 8.6 (17-52). In our study, it was found that those who were under 65 years of age, those who were married, those who were educated by elementary school or higher, those who were equal or higher than the income, those who lived with their wife in the city center, those who have been trained by a health worker about the treatment of the disease had higher both treatment adherence and Modified Morisky motivation and knowledge scores (p<0,001). Conclusion: Of the participants, 46.2% do not use regular drugs. It has been observed that the patients who were trained by a health worker about their disease and treatment process have increased the rate of drug compliance and treatment motivation.