The aim of this study was to assess clinical correlates of the treatment adherence and insight in patients with schizophrenia. Methods: That cross-sectional study included 229 outpatients with schizophrenia who were admitted to the Psychiatry Outpatient Clinic of Health Sciences University Dışkapı Yıldırım Beyazıt Training and Research Hospital. All participants were administered a socio-demographic form, Morisky Medication Adherence Questionnaire, Schedule for Assessing the three components of insight, Brief Psychiatric Rating Scale, Positive and Negative Symptoms Rating Scale, Calgary Depression Scale for Schizophrenia, and Global Assessment of Functioning Scale. Collected data were analyzed with descriptive statistics, Pearson Correlation Analysis, and logistic regression analysis. Results: Poor treatment adherence was associated with male gender, lower insight level, more severe psychotic symptoms, and lower functionality level. The insight score was negatively correlated with the severity of psychotic symptoms, duration of the disorder, and mean antipsychotic dose; but positively correlated with advanced age of onset, and higher functionality level. The logistic regression analysis revealed that functionality level was more predictive on poor medication adherence. Conclusion: Poor treatment adherence and lower insight level were closely associated with more severe clinical symptoms and lower functionality level. It was noteworthy that adherence and insight levels both showed a high predictivity for wellbeing of the patients. Therefore, psychotherapeutic interventions should be implemented to increase treatment adherence and insight in schizophrenia even if the psychotic symptoms show resistance. Further research is needed to clarify clinical associations of the treatment adherence and insight level in patients with schizophrenia.