Background: The phenomenon of deliberate self-harm (DSH) among college students has received increased attention in recent decades. Adopting a psychosocial perspective, this study aims to describe self reported DSH among Chinese medical college students, assess respective associations between uncertainty stress and social capital with DSH, and explore the mechanism linking these three phenomena. Methods: A cross-sectional survey employing multi-stage, sampling was conducted. 4446 undergraduate students were recruited from 22 participating Chinese medical universities. Perceived stress from uncertainty and social capital were assessed among the students. The Chi-square test and multiple logistic regression models assessed correlates of DSH. Relationship among social capital, uncertainty stress, and DSH were examined by means of Structural Equation Modeling. Results: The prevalence of DSH in the past 12 months among Chinese students was 9.6%. The most common types of physical DSH reported were scratching, cutting, and pinching. Age (chi(2)=26.63, p < 0.01), gender (chi(2)=30.24, p < 0.01), major field (chi(2)=28.13, p < 0.01), and annual household income (chi(2)=11.10, p < 0.05) were statistically associated with DSH. Uncertainty stress is a unique correlate of DSH, and shows a stronger association than do three certainty stressors. Social capital is also a strong correlate of DSH, especially cognitive social capital. Moreover, social capital may be indirectly associated with DSH through impacting uncertainty stress. Limitations: This study was a cross-sectional and thus could not evaluate causal relationships. Conclusion: We recommend that a DSH intervention study should target uncertainty stress management and social capital accumulation. This study provides scientific evidence and theoretical foundation for future DSH interventions, with a view to enhancing the mental health of medical college students. (C) 2016 Elsevier B.V. All rights reserved.