Treatment of attentional disorders in America has increased dramatically in recent years. This trend is accounted for partly by lengthening the duration of treatment into adulthood for some individuals as well as by increased treatment among girls. Beyond these factors, the role of economic status, race, and geographic region to explain the variation in methylphenidate use is not well understood. Computerized administrative data were used to explore the influence of several sociodemographic factors on the prevalence of methylphenidate use. The data source consisted of Maryland Medicaid prescription drug reimbursement claims data for FY1991 for children ages 5 to 14 years. In effect, the study was restricted to a sample of patients with limited income. The study aims included (1) measuring gender-, age-, race-, and region-specific methylphenidate prevalence for this restricted income population; (2) comparing the Caucasian:African-American (C:A-A) ratio for methylphenidate with the C:A-A ratio for several drug therapies having non-psychotropic uses, specifically the anti-asthma drug, theophylline, and antibiotics for infections; and (3) estimating the average daily dose of methylphenidate from prescription claims data. Total drug-specific prevalence among the 5-14 year olds was 2.2 percent for methylphenidate while age-specific prevalence varied from 0.4 percent (5 year olds) to 3.4 percent (9 year olds). The gender ratio was 3.7:1 (M:F), confirming the increasing trend for girls to receive this medication. Substantial variation across eight defined regions of the state was observed. Racial differences were pronounced: African-Americans were 2.5 times less likely to receive methylphenidate than Caucasian youths. As hypothesized, non-psychotropic drug use was distinctly different from psychotropic drug use in terms of race: theophylline was 1.5 times more likely to be found for African-Americans than Caucasians, whereas antibiotic prescriptions were 1.5 times more likely to be prescribed to Caucasian youths. Average daily dose of methylphenidate was estimated to be 18.7 +/- 10.4 mg for 5-9 year olds and 26.8 +/- 14.0 mg for 10-14 year olds. This brief report confirms the typically lower rate among African-American Medicaid youths for most prescription drugs. The dramatic racial disparity for the psychotropic agent methylphenidate is a new and compelling finding which should be verified among other economic groups. Diagnostic, referral, and cultural bias should be ruled out as possible explanations for the observed differences.