Extended lymph node dissection during radical prostatectomy for prostate cancer remains a disputed area. Sentinel lymph scans help identify the first lymph node stages in the lymph drainage of the prostate. This study was designed to investigate the detection rate of lymph node metastasis by extended lymph node dissection and sentinel lymph node scanning in patients undergoing radical retropubic prostatectomy (RRP) for localized prostate cancer. In this study at our department from 2005 to 2006, a total of 108 patients with localized prostate carcinoma were treated with radical prostatectomy including extended lymph node dissection. A sentinel lymph node scan with 160 MBq of technetium-99m-Nanocoll (Tc) was performed 1 day before surgery. A C-Trak gamma probe (AEA Technologies, Morgan Hills, CA, USA) was used intraoperatively to detect the sentinel lymph nodes. Scan findings were correlated with tumor stage, Gleason score, prostate-specific antigen (PSA) level, and histological lymph node status. Scans revealed sentinel lymph nodes on the film 2 h after Tc administration in 98 of 108 patients (91%). Histologically proven lymph node metastases were detected in 15 of those 98 patients (15%) with a positive sentinel scan. Those 15 patients had a PSA level greater than 10 ng/ml or a Gleason score greater than 6 and at least a pT2 tumor. Specifically, six patients had a pT2 tumor, and nine patients had a pT3 tumor. Of patients placed in a risk group defined as PSA above 10 ng/ml or Gleason score greater than 6, 15 out of 50 patients (30%) had sentinel positive lymph nodes with metastasis. These data suggest that extended sentinel lymph node dissection helps identify lymph node metastasis in patients with PSA above 10 ng/ml or a Gleason score above 6 in 30% of cases. Further studies will show whether these numbers will hold true in patients undergoing radical prostatectomy for prostate cancer.