This study compares ratings obtained with an itemized clinician-rated symptom severity measure--the 24-item Brief Psychiatric Rating Scale (BPRS24)--with a Physician Global Rating Scale (PhGRS) and a Patient Global Rating Scale (PtGRS) in assessing treatment outcomes in patients with schizophrenia (SCZ). A total of 91 patients (31 inpatients and 60 outpatients) with SCZ were enrolled in a feasibility study of the use of medication algorithms in the treatment of SCZ. Clinicians completed the BPRS24 and the PhGRS; patients completed the PtGRS at each visit. The analyses reported here were conducted using the original BPRS18 and four items from the BPRS18 that rate the positive symptoms of psychosis (the Positive Symptom Rating Scale or PSRS), comparing anchored with global rating scales and with one another. The PtGRS had the lowest effect size (0.8) and was negatively correlated with the other ratings in inpatients. The PhGRS was significantly correlated (0.46) with the BPRS18, but the same person completed both ratings. The effect size of the PhGRS (0.6) was generally lower than with the BPRS18 (1.4) in differentiating responders from non-responders. On average, the PSRS had a slightly lower effect size than the longer itemized BPRS18, but the results support its use as a quantitative rating in circumstances where it is not feasible to routinely use a lengthier scale.