PURPOSE: To evaluate the biochemical control rate and the rate of side effects after performing permanent brachytherapy of localized prostate cancer. MATERIALS AND METHODS: 67 patients with localized prostate cancer were treated with brachytherapy between April 2007 and December 2008. Of these, 43 patients who were followed up and did not receive external radiotherapy were evaluated for the change in prostate specific antigen (PSA) level and the occurrence of side effects. In total, 18 patients were classified as low risk, 19 patients as intermediate risk, and 6 patients as high risk. The prescription dose was 145 Gy. RESULTS: A PSA increase greater than 2 ng/mL occurred in 2 patients (4.7%). Radiation Therapy Oncology Group (RTOG) grade 1 and 2 acute urologic complications (UC) occurred in 40 and 3 patients, respectively. Further, 5 patients had RTOG grade 1 acute rectal complication (RC). The numbers of RTOG grade 1, 2, and 3 chronic UC were 1, 4, and 1, respectively. The numbers of RTOG grade 1, 2, and 4 chronic RC were 5, 10, and 3, respectively. The statistically significant risk factors (RF) of acute RC were the minimal dose in the most irradiated 0.1 cc volume (D0.1CC, p=0.041) and absolute volume receiving 150% of the prescribed dose (V150cc, p=0.038) in the entire rectum (ER). The percentage (V100%, p=0.019) and absolute volume (V100cc, p=0.047) in the involved rectum (IR) were also statistically significant. The RF of chronic RC were V100% (p=0.011) in the ER and the D0.1cc (p=0.049), V100cc (p=0.023) in the IR. The number of used seeds were related with acute UC (p=0.028). CONCLUSION: Permanent brachytherpy of localized prostate cancer showed a favorable short term biochemical control rate. As such, selective intermediate and high risk patients can be managed with permanent brachytherapy. The effort to reduce rectal complication is also necessary.