Prostate specific antigen (PSA) has been used an excellent diagnostic indicator, but its low cancer specificity has been pointed out. In this study, we investigated whether or not the use of Prostate specific antigen density (PSAD) in combination with free/total (F/T) ratio could improve biopsy indication in patients with abnormal PSA levels. Investigated were 428 patients undergoing prostate biopsy in our institution between January 2001 and September 2004, in which PSA levels were 4-20 ng/ml, and F/T ratio and prostate volume (hereinafter 'PV') could also be measured. At the cut-off values of 0.15 for PSAD and 0.25 for F/T ratio, the specificity and sensitivity were 37.7% and 85.5%, respectively, with PSAD alone; 20.1% and 91.8%, respectively, with F/T ratio alone; and 46.5% and 100%, respectively, with PSAD and F/T ratio. These results indicated that PSAD in combination with F/T ratio could also be an excellent biopsy indicator.