 Aims The aims of this study are as fallows.  To assess the knowledge regarding substance abuse and ill effects among P.U. students.  To find out the association between knowledge regarding substance abuse among P.U. students with their selected socio-demographic variables.  Materials and methods  Study design: A cross sectional descriptive study design.  Target population: All PU Students who were studying in the Bagalkot City.  Accessible population: all P.U. Students who were studying at Vaghdevi P.U.College of Bagalkot.  Sample size: P.U. students who were studying in Vaghdevi P.U.College of Bagalkot were selected by using stratified random sampling technique.  Data collection instrument and technique: study was conducted by self administered knowledge questionnaire.  Data analysis: data was organized and analyzed by using descriptive statistics like mean, median and frequency distribution. And in this study inferential statistics is also used like chi-square test to test research hypothesis.  Results After collection, the data were organized and analyzed with the help of mean, median, frequency distribution and percentage. The socio-demographic characteristics of the P.U.students were as fallows.78 % of students’ age was 17 years, 68% students were males,84% of students belonged to Hindu religion.62% of fathers of participants’ educational status was degree and above. 32% of mothers of participants’ educational status were PUC. 40% fathers of students’ were government employees. 46% mothers of students’ were house wives. 46% of students’ family income was 20,000 and above. 76% students were residing in urban area. 58% of students’ type of family was nuclear family. 88% of students’ family members had no history of substance abuse. 60% students had no previous information regarding substance abuse. Percentage distribution of knowledge of students, 16% students had poor knowledge, 82% students had good knowledge and only 2% students had excellent knowledge regarding substance abuse. There was no significant association between knowledge and selected socio demographic variables except sex of the students.  Conclusion After thorough analysis of the data, researcher concluded that students’ knowledge regarding substance abuse should be increased in order to promote their health and there by avoid the consequences occurring due to substance abuse.