Throughout the course of chronic diseases such as ankylosing spondylitis, many factors affect disease activity and quality of life. Diet and exercise in these patients have been investigated in various studies. In addition, treatment adherence plays a critical role in improving clinical outcomes and quality of life in the management of chronic diseases.This study aimed to evaluate the effects of adherence to the Mediterranean diet(MEDAS), physical activity level, and treatment adherence on disease activity and quality of life in patients diagnosed with ankylosing spondylitis.A total of 175 patients followed up with an ankylosing spondylitis diagnosis in the rheumatology outpatient clinic of the hospital participated in the study. Mediterranean Diet Adherence Scale, the International Physical Activity Questionnaire–Short Form, the Compliance Questionnaire for Rheumatology,and the Bath Ankylosing Spondylitis Disease Activity Index were utilized and sociodemographic data and disease history were gathered through face-to-face interviews.The study group consisted of 40.6% women. The mean age of participants was 44.6 ± 10.7 years, and a positive and significant correlation was found between age and adherence to MEDAS (r =0.246, p = 0.001). Individuals with higher physical activity levels had significantly lower MEDAS scores (p = 0.027). A positive and significant correlation was found between treatment adherence and adherence to the MEDAS (r = 0.203, p = 0.012). Women had significantly higher disease activity than men(p<0.001).Among socioeconomic variables, active employment status (p= 0.038) and monthly income level (p = 0.045) were significantly associated with disease activity. Quality of life scores were higher in the low-income group (p < 0.001) and in those with chronic comorbidities (p = 0.020).Overall, this study revealed that disease activity in patients with ankylosing spondylitis is influenced by sociodemographic factors such as sex, income level, employment status, and presence of chronic disease. Older individuals and those who were adherent to treatment showed better Mediterranean diet adherence.The findings of thi study  emphasize that in the management of the disease, attention should be paid not only to medical treatment but also to patients’ sociodemographic characteristics, lifestyle factors, and treatment adherence.