The data covered 1992-96. The analysis used chi-square and logistic regression techniques. The participants were 74 percent male, 63 percent white, 36 percent black, 11-20 years of age (average: 15.6 years). Five percent of the sample was assessed in 1992, 19 percent in 1993, 28 percent in 1994, 26 percent in 1995,and 22 percent in 1996. Results revealed a significant increase in methylphenidate misuse over the last 2.5 yeas, from 2 percent in 1992-93 to 12 percent in 1994-96. The increase was greatest in white adolescents, in whom the proportion of users increased from 3 percent in 1992-93 to 20 percent in 1994-96. Misuse of this substance did not differ significantly by gender and was not associated with a specific drug of choice. Misuse of other prescription or over-the-counter medications did not change during the study period either. Findings indicated a significant increase in methylphenidate misuse, especially in white adolescents and suggested the need for care in considering using methylphenidate to treat adolescents at risk of drug abuse. Tables and 40 references (Author abstract modified)