The primary objective of the study was to investigate the criterion validity of the Cognitive Drug Research (CDR) computerized system in assessing cognitive functioning among persons with brain injury or other organic illness. Understanding the cognitive effects of pharmacotherapy is important in improving long-term rehabilitation outcomes in persons with organic disorders. The CDR system evaluates cognitive skills of attention, short-term or working memory, long-term memory, and visuomotor and motor functioning. For validity testing, correlation coefficients were obtained from an analysis of CDR scores to IQ and Folstein Mini-Mental State Exam (MMSE) scores. Subtests of the CDR system that correlated with the MMSE were choice reaction time (R = -0.542, p = 0.04), spatial working memory (R = 0.938, p = 0.01), and word recognition (R = -0.949, p = 0.01). These tests primarily measured attention and working memory. Correlations between the CDR and IQ scores were not evident. In summary, the data suggest the CDR assessment system has high patient acceptability by persons with traumatic brain injury, and is a useful tool in assessing certain domains of cognition, specifically short-term memory, discrimination, and identification skills.