Inclusion Criteria:

1. Biopsy proven prostate cancer within last 12 months. Pathology must be reviewed at M.D. Anderson Cancer Center (MDACC).
2. 1992 American Joint Committee on Cancer (AJCC) clinical stage T1c-2b on digital rectal exam with biopsy Gleason sum of 7 and PSA < 20 ng/mL (i.e. PSA 19.99 ng/mL or less)
3. 1992 AJCC clinical stage T2b on physical exam with biopsy Gleason sum of 7 or less and/or PSA < 20 ng/ml
4. 1992 AJCC clinical stage T1c-2b on digital rectal exam with biopsy Gleason sum of 7 or less and PSA > 10 but less than 20 ng/ml (i.e. 10.01-19.99 ng/mL). PSA used for protocol eligibility should be obtained within 30 days of protocol enrollment.
5. No evidence of metastatic disease on bone scan within 3 months of study enrollment.
6. No evidence of metastatic disease on pelvic computed tomography (CT) or magnetic resonance imaging (MRI) within 3 months of study enrollment.
7. Zubrod performance status < 2.
8. Must be able to understand protocol and adhere to follow-up initially at 3 months post-radiation and then at 6 month intervals for first two years and annually thereafter.
9. Patient must be able to undergo adequate daily trans-abdominal ultrasound localization (B.A.T.) or other image-guided localization of the prostate during radiation course.
10. Patients will be allowed to participate in other protocols if they are eligible and the other protocols do not interfere with participation in this protocol.

Exclusion Criteria:

1. Patients who do not meet the inclusion criteria. Specifically, patients with all the following features: clinical T1c-2a and Gleason sum of 6 and PSA </= 10 ng/ml. Patients with one or more of the following features: clinical T2c, or Gleason 8-10, or PSA > 20 ng/ml are not eligible.
2. Prior androgen suppression therapy. (Prior finasteride and saw palmetto allowed but must be discontinued prior to enrollment. Biopsy and PSA must be documented prior to finasteride use.)
3. Previous or concurrent malignancies other than basal or squamous cell skin cancers unless disease-free for 5 years or more.
4. Prior pelvic radiation or chemotherapy. Patients who received chemotherapy for non-prostate cancer malignancies over 5 years prior will be eligible.
5. Prior or planned radical prostate surgery.
6. Patients with clinical evidence or biopsy-proven extracapsular extension, seminal vesicle involvement, or lymph node involvement will be excluded. Patients with radiographic evidence of nodal or bone metastasis will be excluded.
7. Other histologies such as small cell carcinoma, sarcomatoid or ductal variants are not eligible.
8. Patients with any Gleason grade 5 disease on biopsy will not be eligible.