In the metastatic process, various cell-cell adhesion molecules seem to play an important role. E-cadherin, a transmembrane protein with an extracellular and an intracellular domain, is one of the key players involved in cell-cell adhesion. The function of E-cadherin in preventing metastasis in tumour development is believed to be dependent on intracellular catenins. In a previous study, the expression of E-cadherin was examined in a series of human breast carcinomas. In that study, down-regulation of E-cadherin failed to correlate with lymph node and/or distant metastasis. In the present study, the expression of alpha-, beta-, and gamma-catenins has been examined in a subset of the same tumours in order to evaluate their possible role in breast cancer metastasis. Tumour tissues from 90 primary breast carcinomas were immunostained for alpha-, beta-, and gamma-catenins. Reduced or absent immunoreactivity in the tumour tissue was seen in 63 (70.0 per cent) for alpha-catenin, in 50 (55.6 per cent) for beta-catenin, and in 50 (55.6 per cent) for gamma-catenin. Reduced expression of each of the catenins alone failed to correlate to metastasis. However, when all of the four proteins (E-cadherin, alpha-catenin, beta-catenin, and gamma-catenin) were analysed as one group, a significant association was seen between reduction in immunoreactivity of at least one of these four proteins and the presence of metastases. These results indicate that if one of these proteins is down-regulated, the function of the others in suppressing metastasis is altered. A significant association was seen between lobular invasive tumours and beta-catenin expression.