Lymph node status in prostate cancer is not only of prognostic but also of tremendous therapeutic relevance. In case of positive lymph nodes (N+), common standards demand the renunciation of local curative therapy (such as radiotherapy or radical prostatectomy) and hormonal withdrawal, or an appropriate adjuvant therapy can be planned (for example, early androgen ablation). But none of the currently available means of radiologic imaging (CT, MRT, PET-CT) provides sufficient identification of lymph node (micro)metastases (< 5 mm). Also, predictive nomograms which are based on data from limited pelvic lymph node dissection (PLND) do not offer a sufficient grade of reliability. However, the limitation of the dissection area results in missing about 50-60% of N+ patients. In addition, the preoperative diagnostics often underestimate the true pathological stage. Presently, it seems that only the histological detection of lymph node metastases by methods with high sensitivity, like sentinel lymph node dissection or extended PLND, are suitable for lymph node staging in prostate cancer. The disadvantages of extended PLND are a high operative effort and increased complication rate. Therefore, sentinel lymph node dissection seems to strike a balance between high sensitivity and low complication rate.