The study was conducted in response to the lack of epidemiological data in recent time on the use of psychoactive substances by adolescents in metropolitan Lagos-a city unique for its socio-economic profile. We considered some methodological issues omitted in several previous studies. A total of 4,286 school pupils (mean age 15.2) were anonymously administered a Self-Report Questionnaire to ascertain a range of key drug use factors in lifetime and 1-year periods. The rate of use of most of the 14 substances investigated was much higher than reported in any other study on comparable population sample. We found that 61.8 and 32.1% of respondents have used one or more substances in their lifetime and in the past 1 year, respectively. High lifetime rates of use were found for common stimulants: coffee, kolanut, and prescription drugs (barbiturates and minor tranquilisers). The rate of use of proscribed addictive substances, cannabis, heroin, and cocaine, ranged between 4.0 and 4.8%. Missing data and non-response rates were few; however, social acquiescence, under and over reporting, could be mitigant to estimation of rates and patterns of use. We advocate properly articulated school-based educative programmes that can facilitate drug demand reduction.