Hypertension is one of the most common worldwide health problems, medication adherence is a major public health concern and leads to considerable morbidity, mortality, and healthcare costs. Hence, it is considering a serious challenge for the patients as well as for caregivers. The main objective of this study was to an Investigating Medication Adherence and Illness Perception Among Patients with Hypertension in Al-Nasiriyah Teaching Hospital. A quantitative descriptive cross-sectional design was performed among 424 adult hypertensive patients attending hypertension clinics in Al-Nasiriyah Teaching Hospital in Al-Nasiriyah, southern Iraq. The data were collected over a period of three months from April 6th, 2022, to July 1st, 2022, by using a questionnaire includes three parts, related to Socio- Demographic and clinical data, eight item-Morisky Medication Adherence Scale (8-MMAS), and Brief illness perception questionnaire (BIPQ). Data was analysis by using SPSS version 25, descriptive statistics (percentage, frequency, SD, mean) used to describe socio-demographic data, Inferential statistics (chi- square test) was used to assess the association between illness perception and treatment adherence, and Anova used to find the relationship between overall evaluation of (BIPQ), eight item 8-MMAS and Demographical data.