Medication non-adherence remains a major barrier to optimal management of chronic diseases worldwide, leading to increased morbidity, hospitalizations, and healthcare costs. In Libya, data on adherence and its determinants are limited, particularly when comparing the public and private healthcare sectors. This descriptive cross-sectional study assessed medication adherence among 400 adult Libyan patients with chronic conditions attending a public outpatient clinic at Tripoli Medical Center and a private clinic, Al-Mustaqbel Al-Mushreq, over a three-month period. A structured Patient Compliance Questionnaire (PCQ) was administered to evaluate adherence behaviors, clinical outcomes, and patient perceptions. Chi-square tests, t-tests, and logistic regression analyses were applied to identify factors associated with adherence. The mean age of participants was 57.4±0.9 years, with balanced gender distribution. Significant differences were observed between sectors: patients in the private sector reported higher adherence to medication and monitoring schedules (P<0.05), greater perceived improvement since diagnosis (P<0.01), and fewer concomitant diseases (P<0.05). Logistic regression identified older age (OR 1.05, 95.0% CI 1.02-1.08), longer duration of medication use (OR 1.07, 95.0% CI 1.01-1.14), and unemployment or retirement status (OR 1.54, 95.0% CI 1.10-2.17) as positive predictors of adherence, whereas poor self-perceived health status was associated with lower adherence (OR 0.68, 95.0% CI 0.49-0.94). These findings highlight the influence of socio-demographic and clinical factors on medication-taking behaviors and underscore the importance of targeted interventions. Integration of clinical pharmacy services, including patient education, counseling, and follow-up, may improve adherence and health outcomes in Libyan chronic disease populations. Strengthening public sector resources and implementing adherence-focused strategies are essential to reducing disparities and enhancing overall care quality.