Extraction of glycolipid component from hypertrophic and cancerous prostatic tissue were performed using chloroform-methanol solution and isopropanol-hexan-solution. The extract was separated into the "upper phase" and "lower phase" by Folchs fractionation technic. Each fraction was conjugated with acid treated salmonella minesota and than it was injected subcutaneously, intra-peritoneally and finally intravenously to BALB/c mice. Spleen cells from immunized mice were fused with P3X63, and antibody APG1 was obtained. APG1 shows a preferential reactivity towards prostatic tissue by the immunohistochemical analysis. Furthermore, the immunohistochemical analysis using enzyme and acid treated tissue and TLC immunostaining indicate that this monoclonal antibody specifically recognizes the sialylglycochain expressed in the prostatic tissue.