This article reviews information related to the BRMS1 (BReast Metastasis Suppressor 1) metastasis suppressor gene. BRMS1 was identified by differential display comparing metastasis-suppressed chromosome 11 hybrids with metastatic, parental MDA-MB-435 human breast carcinoma cells. BRMS1 has subsequently been shown to suppress metastasis, but not tumorigenicity of human melanoma cells. The murine version, Brms1, also suppresses metastasis and exhibits a high level of homology to the human gene at the structure, nucleotide and amino acid levels. The mechanisms of action remain to be determined; however, BRMS1 transfectant cells have restored gap junctional intercellular communication. Recent data suggest that BRMS1 is part of the mSin3A histone deacetylase complex.