Adolescents (10 to 18 years old) from a rural area in the state of Rio de Janeiro, Brazil were tested using the Behavioral Assessment and Research System (BARS) to evaluate their performance. Participants were drawn from two areas--a school serving farm children (rural N=38) and a school serving children from a city within this area (urban N=28). These children were drawn from an ongoing study being carried out by Fundação Oswaldo Cruz where rural and urban participants were matched for age, sex, and level in school. For this ongoing study, the participants had been interviewed to determine their occupational history, especially their activities that might involve exposure to pesticides. Interview responses were used to assign an exposure index to each participant. While a few BARS performance measures suggested behavioral impairments for the rural versus the urban participants, a stronger and more consistent association between BARS measures (especially impairment of tapping, digit span, and selective attention) and level of exposure to pesticides was noted when the exposure index was entered into a multiple linear regression analysis. Exposure appeared to be especially strong for the youngest participants (10-11 years old). The relationship between these behaviors and the exposure index was stronger than the relationship between behaviors and either age or sex.