Glycoconjugates in the secretory epithelial cells of the rhesus monkey (Macaca mulatta) prostate gland were investigated using lectin histochemistry. The monkey prostate possesses cranial and caudal lobes. Histochemical staining with a battery of 8 lectins demonstrated differences in lectin binding patterns of the secretory epithelial cells between the 2 lobes. BS-1 bound exclusively to the cranial lobe, and PNA bound exclusively to the caudal lobe. DBA bound exclusively to a number of the secretory epithelial cells of the caudal lobe. In addition, both lobes showed binding with Con-A, RCA-1, WGA and S-WGA, but were negative for binding with SBA. Specific lectin binding patterns suggest a differing carbohydrate composition for each region, and a biological difference between the cranial and caudal lobes of the rhesus monkey prostate.