Lymphoscintigraphy (LS) has been performed for 8 years in patients of the Sydney Melanoma Unit, to define lymphatic drainage patterns. Over the past 2 years, LS has also been used to locate the sentinel lymph node prior to surgery. Our technique for LS and subsequent sentinel node biopsy has an accuracy of 97%. All sentinel nodes must be marked to ensure the successful application of the sentinel biopsy technique. We have found that the axilla and groin average just over one sentinel node per draining node group for lesions on the trunk and upper limb, but have noted that drainage to the groin differed when lower limb lesions were studied. Because of the anastomosis of lymph vessels in the upper thigh, multiple sentinel nodes are identified in the groin in some patients. We have found an average of three sentinel nodes in the groin when lymph drainage from lower limb lesions was studied with LS. This difference demands a modification of the LS technique, with early imaging of the groin nodes to identify all sentinel nodes in each patient. The depth of the sentinel nodes can also be measured and the location of all interval nodes marked on the skin. This ensures that all sentinel nodes and interval nodes can be removed at the time of surgery.