OUTLINE: This is a multicenter study. Patients receive transrectal ultrasound guided radioactive I-125 seeds implanted into the prostate. At least one week prior to implant, patients undergo transurethral ultrasound study to determine the volume of prostate. Following implantation, seeds that have extruded into the bladder or lodged in the urethral wall are retrieved, and extra seeds may be implanted into identified "cold spots" for uniform seed distribution. Prostate rebiopsy is required before starting hormonal therapy for local progression or biochemical failure without clear focus of progression. Quality of life is assessed every 3 months for 1 year, then every 6 months for 1 year, and then annually for 3 years. Patients are followed every 3 months for 1 year, then every 6 months for 2 years, and then annually thereafter.