While the supply side dimensions of the international drug problem have been recognized for decades, the demand side has traditionally been considered a domestic issue, not conducive to international assessment. The present report, based on data obtained primarily from the annual reports questionnaires (ARQ) received by UNDCP up to February 1999, presents not only the supply side data but also the demand side data, in an effort to give a balanced approach in the assessment of the drug problem. In addressing the global trends in illicit drug supply and trafficking, the report discusses cultivation, manufacture, trafficking routes, methods of transportation and seizures. On the demand side, the report focuses on global trends, the extent of drug abuse, drug abuse among youth and prison populations, modes of intake and costs and the consequences of drug abuse. Comprehensive statistical tables, presented for multiple years, will greatly facilitate comparative studies.