Objective. The purpose of this trial was to study the use of terazosin in nonbacterial prostatitis/prostatodynia, and to evaluate a new symptom score sheet for this disease. Methods. Twenty-five patients who presented with lower urinary tract symptoms suggestive of prostatitis were evaluated for evidence of bacterial infection by Meares-Stamey criteria and found to be negative. They were then treated with the alpha-blocking drug terazosin in doses from 1 to 10 mg. A symptom score index for prostatitis was developed, tested in these patients, and validated against patients with benign prostatic hyperplasia. Normal control patients, who presented for vasectomy, were studied as well. Results. Nineteen patients (76%) responded to one month's therapy, with 11 (58%) remaining asymptomatic three months later. The symptom score index, as measured by Cronbach's alpha measure of index reliability, was excellent at 0.78 and logistic regression analysis demonstrated each prostatitis question to have independent validity (P < 0.001) but not to the extent of the combined score. Conclusions. Terazosin appears effective in treating patients with nonbacterial prostatitis/prostatodynia. This new symptom score is one way to evaluate and track patients with this disease. A randomized, placebo-controlled clinical trial has been initiated to study this.