We analysed the differential expression pattern of the three distinct TAG-72 carbohydrate epitopes detected by monoclonal antibodies (MAbs) B72.3, CC83 and CC49 in a consecutive series of 114 patients with primary breast cancer and in 39 synchronous lymph node metastases. B72.3, CC83 and CC49 were expressed in respectively 81 (71%), 68 (60%) and 96 (84%) of the 114 cases. Interestingly, MAb B72.3 was significantly expressed in a subgroup of patients characterised by larger tumour size (p=0.013), lymph node metastasis (p=0.0002), high histopathological grade (p=0.006), high cell kinetics (p=0.04) and advanced clinical stage (p=0.0019). In 20 (51%) of the 39 pairs of matched primary breast cancers and synchronous lymph node metastases, TAG-72 was expressed in the tumour but not in the corresponding metastatic lymph node; tumours with TAG-72-negative lymph nodes appeared to be clinicopathologically more aggressive. CC49, the most immunoreactive and widely used MAb, was not detected in 34% of the metastases of expressing primary tumours. All three MAbs were found in a significantly lower per cent of synchronous metastases with respect to primary tumours (p<0.001).