Abstract The study investigated the relationship between peer pressure, drug abuse and deviant behaviour among students in tertiary institutions in Rivers State. The study adopted a correlational research design. Three research questions and three null hypothese guided the study. The population of the study comprised all the 23429 students in 200 and 300 level from Ignatius Ajuru University of Education (IAUE) and Rivers State University (RSU). The sample for the study consisted of 400 students. Taro Yamane formula was used to get the sample size. The researcher developed three instruments, namely; Peer Pressure Scale (PPS), Drug Abuse Scale (DAS) and Deviant Behaviour Scale (DBS). In order to ascertain the face and content validities of the instruments for the study, it was submitted presented to experts in Measurement and Evaluation who went through the content and structure of the instrument. To determine the reliability of the instruments, test-retest technique was used. Pearson Product Moment Correlation was used to answer the research questions and test the null hypotheses at 0.05 level of significance. The result revealed that direct peer pressure, indirect peer pressure and drug abuse significantly related to deviant behaviour among students in tertiary institutions in Rivers State. Based on the results, the researcher recommend among others that tertiary institutions should implement peer mentoring and counselling programmes that target students’ social interactions.