ObjectiveThis cross-sectional study aimed to explore the magnitude of this problem and the explored the psychosocial risk factors of RSB among Nepalese undergraduates.Study DeignCross-sectional studyStudy participants373 undergraduate hostellers residing in hostels of Kathmandu Metropolitan city were selected randomlyData AnalysisChi-square test and unadjusted odds ratio was calculated at 5% level of significance to identify the factors associated with risky sexual behaviour. The factors found to have statistical significance (p<0.05) in chi-square test were subjected to the final model of multivariable logistic regressions.ResultOne third (35.2%) of the participants were practicing towards risky sexual behaviours. The socio-demographic factors such as: age; gender; ethnicity; relationship status; education of father; education of mother and pocket money, Likewise lifestyle and psychological factors such as: peer pressure have any sexual relationship; smoking status; and alcohol consumption of the participants were found to be statistically significance with status of practice towards risky sexual behavior.