To assess the structural stability of positive and negative symptom ratings, we rated 40 schizophrenic inpatients on the Brief Psychiatric Rating Scale (BPRS) and the Scale for the Assessment of Negative Symptoms (SANS) at medication-free baseline and after 4 weeks of neuroleptic treatment. Positive symptom variables consisted of six BPRS items, and the negative symptom variables consisted of the five SANS subscale global scores. On principal components analysis, a three-factor, oblique-rotated solution resulted, with a negative symptom factor, a positive symptom factor, and an unstable behavioral agitation factor. The pre- and posttreatment factor loading patterns were similar. The findings suggest that BPRS-positive symptom items and the SANS measure distinct clinical dimensions and that the construct is stable, as demonstrated by minimal structural change with time.