PURPOSE: A sentinel lymph node biopsy (SLNB) has become the standard care for the staging of axilla in breast cancer and the increase in body weight with age has an inverse relationship to its success. Therefore, the characteristics of patients who underwent a SLNB, and the relationship of the influences of Body Mass Index (BMI) and age, were evaluated using lymphoscintigram visualization in a sentinel lymph node biopsy (SLNB) for breast cancer. METHODS: Between Sept. 1995 and Dec 2003, 238 patients underwent lymphoscintigraphy and SLNB (including full axillary node dissection with SLNB). 205 (86.1%) cases were able to be visualized by lymphoscintigraphy, But the remaining 33 (13.9%) were not. A combined technique (radioisotope and blue dye) was used to detect the SLNs. The BMI for each patient was calculated from height and weight data (kg/m2). RESULTS: A SLNB was attempted in all cases, but 5 failed. Of the 238 cases, the lymphoscintigraphy visualization was successful in 205 (86.1%) and failed in 33 (13.9%). The mean weight and BMI were significantly higher in the failure group. The success of a SLNB was inversely related to the BMI. When the subjects were divided into two group ac-coding to age (<50 year-old versus > or =50 year-old), this relationship was more pronounced in the > or =50 year-old group. CONCLUSION: The age and BMI of the patient influences the detection of the sentinel lymph node on a lymphoscintigram. There was no influence on the sentinel lymph node biopsy with increasing BMI and age. Therefore, increased age and/or BMI alone do not appear to be contraindication for a sentinel lymph node biopsy in older or overweight patients.