Marijuana is one of the most commonly abused substances among adolescents. Its use has led to addiction, poor concentration and poor performance in schools, thefts, organized crime, violence, mental illnesses, injuries, infections, and behavioral disorders. Aim of this study was to determine the prevalence, perception, and peculiarities of marijuana use among adolescents attending secondary schools in Sagamu, South-West Nigeria. A descriptive, cross-sectional design was used. 388 respondents were selected by a multi-stage sampling technique. A validated, semi-structured questionnaire with Cronbach’s alpha of 0.72 was used to collect data. Statistical analysis of the prevalence was based on frequency and percentage, expressed in tables and figures. A 4-point Likert scale was used to collect information on the students’ perception. Logistic regression analysis of SPSS version 23 was used to assess the correlation between marijuana use and its prevalence. The mean age of respondents was 15.46±1.37years. Over half (56.2%) of the respondents were female, 74.5% were Christians, 84.0% were Yoruba, and 28.4% were in senior class one (grade 10). 4.6% of the respondents had an illiterate dad and 3.9% had an illiterate mum. A majority of the respondents’ fathers (70.6%) and mothers (78.1%) were self-employed. Among the respondents, the prevalence of marijuana use was 7.2%. Perception of marijuana use was high as the items in the perception analysis fell within the Likert scale interval of strongly agree and agree. There was no significant association between the students’ perception and marijuana use (R=-0.051; p=0.31). With no significant association between high perception and marijuana use, the respondents’ marijuana use was not influenced by their perception but by a particular aim - exam success which is very peculiar. Counselors and social workers should be engaged and strengthened in secondary schools to help promote abstinence from marijuana use.