This program was implemented with the purpose of eradicating large numbers of opium poppy and marijuana fields in Mexico, a primary source of the heroin and marijuana available in the United States. The U.S. General Accounting Office (GAO) is required to review this program and investigate the effectiveness of assistance provided through the U.S. international narcotics control program. Specifically, GAO examined the extent to which (1) the program has reduced Mexican opium poppy and marijuana crops, (2) aircraft and other resources provided by the United States have been used effectively, and (3) bilateral agreements provide for the cooperation needed to eliminate opium poppy and marijuana crops quickly and efficiently. Findings were: (1) that maintaining aerial eradication at current levels will not eliminate Mexico as a major source of heroin and marijuana; (2) that the aircraft provided was under-used because of deficient maintenance and insufficient numbers of pilots due to low salaries; and (3) that the formal agreements between the United States and Mexico do not address the frequency and scope for aerial surveys to help gauge the magnitude of illicit drug cultivation, include reasonable annual eradication targets, and provide for validation and evaluation of program accomplishments. Among the recommendations for improvement of the program were to rectify all of the above deficiencies. 7 tables, 3 figures, and appended comments.