BACKGROUND: Defensins are small (3.5~5 kDa) cationic antimicrobial peptides that have a broad spectrum of activity that includes gram-negative bacterias, yeasts and enveloped viruses. The defensins contain six cysteine residues forming three disulfide bridges depending on the spacing of the cysteine residues and the connectivity of the disulfide bridge, defensins are classified into two families, the alpha-defensins (HNP) and beta-defensins (HBD). Recently two human epithelial beta defensins, HBD-1 and HBD-2 have been identified. HBD-1 has been detected in a number of normal mucosal sites, but HBD-2 is highly restricted in its expression by inflammatory stimulations. we invesigated the expression of hunam beta defensin in human male urogenital organs. METHODS: Specimens of normal human male testis, epididymis, prostate, seminal vesicles, vas deferens, urethra, bladder, ureter, kidney, pyelonephritis, epididymitis, clear renal cell carcinoma and transitional cell carcinoma of bladder were obtained as discarded material from urological surgery. Each sample was stored at snap frozen in liquid nitrogen subsequent to RNA extraction. Reverse transcription polymerase chain reaction (RT-PCR) was used to semiquantitate HBD-1 and HBD-2 mRNA using the housekeeping gene beta-actin as an internal control. Southern blotting and sequencing showed HBD-1, 2 expressions in male urogenital organs. RESULTS: We checked the expression of HBD-1, 2 mRNA in all specimen of normal human male urogenital organ, pyelonephritis, epididymitis, clear renal cell carcinoma and transitional cell carcinoma of bladder by RT-PCR and southern blotting analysis. We checked the homolgy of HBD-1, 2 by bands sequencing. CONCLUSION: Our study indicated that the normal male urogenital organs, infection and neoplasm in male urogenital organs expresses antimicrobial peptides. These may play an important role in the prevention of infections by bacterias, antimicrobial effects in infection and anticancer effects in neoplasm of male urogenital organs. These natural endogenous antibiotic peptides could be developed as novel therapeutic agents for fighting infections and neoplasms of the human male urogenital organs.