Ecstasy is a methamphetamine derivative becoming increasingly popular throughout the world, particularly among adolescents and young adults. This study surveyed a representative sample drawn from cities in different geographical regions in Turkey in 1998 and 2001. The questionnaire was administered to a total of 18,556 and 11,911 students in the 10th grade in 1998 and 2001, respectively. This study was carried out among Turkish secondary school students to establish frequency of substance use, the change through the years, and associated factors. The study sample was drawn from 15 cities in 1998 and 9 cities in 2001. The study was carried out between April and June in 1998 and 2001. Questionnaires were administered by a research assistant chosen under the supervision of the specialists in charge of the survey of each city. Questionnaires were applied on the day when final semester examinations were held, in order to minimize absenteeism. The questionnaire administered in the study was adapted from the questionnaires used in the Monitoring the Future study in the United States and the European School Survey Project on Alcohol and Other Drugs. It included questions about demographic characteristics, school life, social contacts, and use of substances. The study found that while the percentage of those who used Ecstasy at least once in their lifetimes was 2.65 percent in 1998, the figure reached 3.31 percent in 2001. Male gender, older age, use of alcohol, cannabis, heroin and cocaine, non-medical use of psychotherapeutic drugs, and participation in a meeting concerning the adverse effects of substance abuse were found to be significant variables predicting "ever use" of Ecstasy in both years by logistic regression analysis. Ecstasy use while low in Turkey, appears to be on the increase and follows a pattern in terms of correlates that is similar to other illicit drugs. Whatever the causes behind the rise of Ecstasy use, creative, personalized, and informative educational programs should be conducted in all educational institutions to curb its use. Tables, references