ObjectiveThe objective of this research was to quantify nonadherence to medication and explore the determinants of nonadherence in patients diagnosed with schizophrenia (SZ) from three countries in Latin America (Bolivia, Peru, and Chile).MethodsThis study was conducted in public mental health centers in Bolivia, Peru, and Chile. The data collected included drug attitude inventory (DAI-10), sociodemographic information, and clinical and treatment characteristics of patients with SZ. Multivariate analysis with multiple linear regression was then performed to identify variables that were potentially associated with the DAI score (dependent variable).ResultsTwo hundred and fifty-three patients diagnosed with SZ participated in the study and 247 fully completed the DAI-10. In the multivariate analysis, medication nonadherence was associated with being a woman (β=−0.16, p=0.029), younger age (β=0.17, p=0.020), younger age at onset of disease (β=−0.17, p=0.019), and lower insight (β=−0.30, p<0.001).ConclusionBeing a female, younger age, younger age at onset of disease, and lower insight were the main features associated with nonadherence. If future longitudinal studies confirm these findings, these factors should not be neglected in Latin American mental health public policies to address the problem of nonadherence.