Substance abuse is a growing societal problem with adolescents being at increased risk. The few studies in Nigerian adolescents have not factored in their knowledge base with regard to the concept of substance abuse. This study determined the indulgence in and knowledge of substance abuse and associated factors among adolescents. This was a questionnaire based study involving 10 to 19year olds recruited from an adolescent summer camp in Anambra state, South-East Nigeria. The data of 276adolescents was analyzed, male-91, 33%, M: F = 1: 2. Mean age was 16.4 ± 1.4years. 13.8% (38) accepted they had abused substances in the past; 74.3% (205) had the correct knowledge of the meaning of substance abuse; 10.1% (28) admitted taking substances for pleasure. The substances taken included Alcohol (67.9%), Cigarette (25.0%), Tramadol (10.7%), Cocaine (7.1%), among others. Multiple substances were taken 28.6% of the time.Age category had no significant association with the abuse of substances (X2-2.656, p = 0.282). Stratified by age category, gender had a significant association with substance abuse in Late adolescence (n = 11; M-9, 81.8%; F-2, 18.2%; X2 = 6.893, p = 0.016) but not Mid-adolescence (n = 27; M - 10, 37.0%; F - 17, 63.0%; X2 = 0.749, p = 0.500). An unacceptable proportion of the adolescents were already exposed to substances/drugs in spite of having suboptimal knowledge. Adolescents need to be educated on substance abuse and its dangers in order to curb this in the society.