Anterior cingulate (ACC) hypo-activity is commonly observed in chronically ill schizophrenia patients. However, it is unclear whether this is secondary to persistent illness and/or medication. METHOD: We examined eight antipsychotic-naïve first-episode patients and matched healthy controls undergoing PET scanning while performing the Stroop task. RESULTS: Group-averaged and single-subject analyses showed ACC activation in both controls and patients, albeit in different sub-regions (paracingulate and cingulate respectively). A direct comparison revealed relative under-activity of the left paracingulate cortex in patients. CONCLUSION: These findings suggest that the more pervasive hypo-activation observed in chronic patients may be secondary to persistent illness and/or medication.