Visualization and biopsy of sentinel lymph nodes play an important role in planning and controlling the therapy of breast cancer. Hitherto two methods-scintigraphy or gamma probe detection after injection of [ 9 9 m Tc]-nanocolloids and visual detection after injection of patent blue dye-are used routinely. There are no conclusive publications elucidating such important parameters as injection site, injection method and colloidal parameters. The present work aims to label Nanocoll ( R) with [ 1 1 1 In] to provide an alternative method, a simultanous one-compound dual-isotope application.Methods: [ 1 1 1 In]-Indiumchloride was buffered with acetate and transferred to the nanocolloid. The colloid labelling reaction was complete after 30min and filtrated through 100nm Nuclepore ( R) filters.Results: Incorporation yield of [ 1 1 1 In]-Indium into the nanocolloid was nearly quantitative, the step associated with the major loss of activity was the particle sizing with a mean yield of 55%.Conclusion: The presented method allows for the routine supply of [ 1 1 1 In]-nanocolloids. Size-filtered [ 1 1 1 In]-Nanocoll ( R) shows the same particle size range as [ 9 9 m Tc]-Nanocoll ( R).