Background and Objectives: Optimal blood pressure control is achieved by medication adherence. This will reduce the risk of associated morbidities and mortalities. The present study aimed to determine medication adherence and its associated factors among hypertensive patients attending different primary health centers (PHC) in Abha, Saudi Arabia (KSA). Methods: A cross-sectional study was conducted among ten different PHCs in Abha, KSA. Simple random sampling procedure was utilized to choose 400 participants. A structured anonymous questionnaire was used in the present study. Analysis of the data was done using the SPSS program, version 23. A logistic regression statistical test was applied to identify the independent associated factors of medication adherence. Furthermore, we have applied Spearman's test to find the correlation between overall B-IPQ score and medication adherence score. Results: A total of 400 hypertensive patients responded in the present survey. More than one-third of the participants (36.3%) were in the high adherence category group, while the remaining participants (63.7%) were either low or medium adherence category. The binary logistic regression analysis revealed that low and medium adherence category is significantly associated with age (adjusted odds ratio AOR = 0.96, 95% CI =0.93-0.99, p = 0.021), married participants (AOR = 0.42, 95% CI =0.33-0.58, p = 0.001), residing at village (AOR = 1.49, 95% CI =1.14-1.73, p = 0.038), and participants with monthly family income of 5000 to 7000 SAR (AOR = 3.06, 95% CI =1.62-5.79, p = 0.001). A negligible positive correlation was revealed between illness perception and medication adherence. Conclusion: The present study revealed that hypertensive patients poorly adhere to their antihypertensive medications. This low adherence is significantly associated with the age, monthly income, people living in rural areas, and married participants. The present study results recommend sustained efforts to implement health education programs and awareness-raising interventions targeted at hypertensive patients. Keywords: medication adherence, hypertension, illness perception, primary health centers, Saudi Arabia