Background: currently the Elderly population is rapidly increasing and with this increment comes more challenges for the healthcare system, non-adherence to medications especially in elderly can lead to economic and human lost that is avoidable by improving patients' compliance and address the related issues leading to the non-adherence. Objectives: 1-assess the level of adherence knowledge and belief to medications. 2-identify the related factors causing the non-adherence. Methodology: A cross sectional study was conducted in primary healthcare centers in Baghdad targeting geriatric age group of both genders attending the primary healthcare centers and having at least one diagnosed chronic disease, the study enrolled10 healthcare centers from both sides of Baghdad. Patients were directly interviewed and data was collected using a questionnaire. Results: The study showed that (83.4%) of the sample (n=385) had low adherence level, this percentage tend to increase as the age increases, no significant association was found with gender variable, and a significant association was found with the age variable. most of the participants has low beliefs level (86%) and only (7%) of the sample scored (high) on knowledge level which was significantly associated with adherence level, (13.5%)of the participants faced high difficulty to adhere to their medication. Conclusions: Elderly patients attending the primary healthcare centers in Baghdad had low level of adherence; most of them did not have enough knowledge about their medications. Patients who scored low level of adherence tend to pay more visits to the healthcare centers.