Emerging large number of patients with chronic diseases, present special challenges for modern health system. Self-treatment may be an alternative approach to meet the healthcare demand, and currently of great interest in many countries. However, whether self-treatment can decrease the use of formal health care, especially outpatient visits, is still not clear. No empirical study has been conducted to examine the relationship between self-treatment and outpatient visits of individuals with chronic diseases under China's unique bifurcated healthcare system. The baseline data of a national survey of Chinese Health and Retirement Longitudinal Study (CHARLS) conducted in 2011-2012 among respondents aged 45+ was used in this study. Survey logistic regression models were applied to explore the association between self-treatment and outpatient visits under the framework of the Anderson Behavior Model among 11,673 respondents. Results showed that Over-thecounter (OTC) medicines consumption was the main mode of self-treatment in China. Respondents with OTC medicines consumption had fewer outpatient visits in the previous month than their counterparts (30.1% vs. 41.0%, p < 0.01). After controlling socio-demographic factors, lifestyles, number of chronic diseases, self-reported health status, depressive symptoms and health insurance, the negative association between OTC medicines consumption and outpatient visit remained significant (OR = 0.45, 95% CI: 0.39, 0.53). These findings suggest that self-treatment, especially OTC medicines consumption, may decrease outpatient visits for adults with chronic diseases in China.