N1, P2 and P300 potentials were studied in 20 cases of cerebral infarction and 47 healthy controls with standard technique of auditory event-related potentials. Healthy controls of both sexes, different ages, education levels and cognitive capacity did not show apparent differences in the latency of p300 (P greater than 0.05, respectively). The patient group, however, revealed significant (P less than 0.001) prolongation of latency of P300 (mean = 409.6 +/- 50 ms) as compared with 28 well matched healthy subjects (mean = 337.7 +/- 24 ms). Although there was some decline of amplitude of P300 in the patient group, the difference between the control and patient groups was not significant (P greater than 0.05). There was significant difference in the Cognitive Capacity Screening Examination findings between the control and patient groups (P less than 0.01), but it seemed that the evaluation of latency of cognition-related p300 might be more objective and sensitive (P less than 0.001).