ObjectiveTo evaluate the factors associated with poor medication adherence in patients with DM and HTN in Peru. Study designA cross-sectional study. MethodsWe analyzed data from the Peruvian Demographic and Family Health Survey from 2014 to 2019. Adjusted prevalence ratios (aPR) and their respective 95% confidence intervals (CI) were estimated to determine the factors associated with poor medication adherence. ResultsWe included 15,184 participants with a known diagnosis of DM and HTN. The frequency of poor medication adherence was 37.1%, with 36.7% among individuals with HTN and 29.2% among individuals with DM. Those belonging to age groups above 30 years (aPR: 0.77; 95% CI: 0.74–0.80, for the group ≥ 60 years) had a lower frequency of poor medication adherence. Meanwhile, being male (aPR: 1.03; 95% CI: 1.01–1.05), lacking health insurance (aPR: 1.08; 95% CI: 1.05–1.10), belonging to lower wealth quintiles (aPR: 1.12; 95% CI: 1.08–1.17, for the first quintile), and living in the mountain region (aPR: 1.09; 95% CI: 1.06–1.12) were associated with a higher frequency of poor medication adherence. These findings were consistent when stratifying by the type of disease. ConclusionThis study showed that poor medication adherence is common in patients with HTN and DM in Peru and is associated with sociodemographic factors, highlighting the importance of public health approaches to improve adherence.