Objective: To study the relationship between the polymorphic (CAG)n micro-satellite of human androgen receptor (hAR) gene and prostate cancer (PCa). Methods: The number of (CAG)n repeats in 107 normal males were measured by a two-step [α-32P]-dCTP incorporated asymmetric polymeric chain reaction (PCR), and the (CAG)n repeats of both malignant and nonmalignant prostate cells in fixed paraffin-embedded tissue (PET) specimen from 36 case of PCa were determined by sequence analysis. Results: The repeats of polymorphic (CAG) n among normal men ranged from 11 to 29, and the most frequent repeat was 22(18. 69%), with 23(14. 02%), 24(10. 28%) and 21(10. 28%) being less frequent. The (CAG)n repeats of malignant prostate cells equaled to that of nonmalignant adjacent prostate tissue cells from the same PET specimen in all 36 PCa, and the (CAG)n repeats in 36 PCa which ranged from 16 to 22 were shorter than that in normal males significantly (P<0. 05), while no significant difference in (CAG)n repeats among variou Objective: To study the relationship between the polymorphic (CAG) n micro-satellite of human androgen receptor (hAR) gene and prostate cancer (PCa). Methods: The number of (CAG) n repeats in 107 normal males were measured by a two -step [α-32P] -dCTP synthetic asymmetric polymeric chain reaction (PCR), and the (CAG) n repeats of both malignant and nonmalignant prostate cells in fixed paraffin-embedded tissue (PET) specimen from 36 case of PCa were determined by Sequence analysis. Results: The repeats of polymorphic (CAG) n among normal men ranged from 11 to 29, and the most frequent repeat was 22 (18.69%), with 23 (14.02%), 24 %) and 21 (10.28%) being less frequent. The (CAG) n repeats of malignant prostate cells equaled to that of nonmalignant adjacent prostate tissue cells from the same PET specimen in all 36 PCa, and (CAG) n repeats in 36 PCa which ranged from 16 to 22 were shorter than that in normal males significantly (P <0. 05), while no significant difference in (CAG) nr epeats among variou