Reaction time (RT) has been used to discriminate individuals with brain damage from controls, but little is known about the relationship between RT and neuropsychological (NP) tests. This relationship was examined 3 ways. First, the mean, median, and SD scores of simple and choice RT for 213 referrals were used as potential predictors of NP impairment in discriminant analyses; cross-validation produced a significant hit rate. Second, the hit rate (NP impairment vs. no) using RT was compared to hit rates using fluency, IQ, and memory measures; the RT rate did not significantly exceed the others. Third, the abilities of RT and of a NP impairment score to classify 28 subjects into brain injury and control groups were compared; the hit rates were not significantly different. Results are interpreted to indicate moderate agreement between RT and NP tests regarding impairment classifications and to suggest roles for RT in NP assessment.