This article reviews the "state of practice" with regard to sentinel lymph node biopsy, a new and evolving technique currently used most commonly for staging of malignant melanoma and adenocarcinoma of the breast. Sentinel lymph node biopsy has the potential to both increase the accuracy of lymph node sampling as a prognostic tool and to decrease the need for unnecessary and morbid extensive lymph node dissection in such patients. The need for close cooperation and planning involving the surgeon and pathologist is stressed, and gross room tissue handling, radiation safety, microscopic examination, and the use of ancillary diagnostic techniques are discussed.