Past research has confirmed the importance of vigilance deficits in schizophrenia. The present investigation examined the temporal relationship between treatment response of acute schizophrenic inpatients' (n = 13) psychopathology and their vigilance performance, using the Continuous Performance Test, at four time points over the course of an acute hospitalisation: at medication-free baseline and then weekly for 21 days after the initiation of neuroleptic treatment. A comparison group of stable schizophrenic outpatients (n = 12) receiving neuroleptics at all assessments were also tested during the same time period. For the acute group we found a significant improvement in both vigilance and symptoms over the course of neuroleptic treatment and the extent of improvement in vigilance performance was correlated with improvements in symptomatology. The control patients exhibited no CPT improvement or symptomatic changes. Because vigilance deficits correlate with poor outcome in schizophrenia, these data suggest that the medication-related changes in cognitive performance early in the course of neuroleptic treatment may provide clues to the expected course of illness in acute patients.