Radiolabelled specific monoclonal antibodies (MAbs) HMFG2 and HMFG1 F(ab')2 and non-specific 11.4.1 and 4C4 F(ab')2 were injected into the webs between the 2nd and 3rd fingers of both hands in 31 patients with clinical diagnosis of breast cancer. We studied 10 patients with clinically obvious axillary lymph-node disease (group A) and 10 patients with clinically negative axilla (group B) using HMFG2, 5 patients with clinically negative axilla (group C) using HMFG1 F(ab')2 and 6 patients with clinically positive axilla (group D) using non-specific 11.4.1 and 4C4 F(ab')2 MAbs. In group A, 7 patients had true positive scans. There were also 3 false negative scans, due to problems related to proper iodination at the beginning of this study. In group B there were 4 true positive scans, 4 true negative, I false positive and I false negative. In group C there were 4 true negative scans. In one patient the radiolabelled antibody was arrested in the middle of the arm, because of lymphatic obstruction. In group D, there were 3 false negative scans with 11.4.1 antibody and 3 false negative scans with 4C4 F(ab')2 MAb. The results of immunoscintigraphy were in accordance with the histopathology and immunoperoxidase staining findings. These results indicate that this non-invasive approach can accurately detect metastatic involvement in the axillary lymph nodes and can be used for the diagnosis and staging of breast cancer.