Breast cancer metastasis suppressor-1 (BRMS1) is a putative antimetastatic gene. However, results relating its expression to the prognosis of breast cancer are still controversial, and all studies carried out to date have failed to show a relationship between the expression of BRMS1 and axillary lymph node metastasis in breast cancer. It has been recently suggested that BRMS1 may exert its physiological role through the modulation of apoptosis. In order to test this hypothesis, we studied the expression of BRMS1 and genes known to be directly related with apoptosis in human breast carcinoma. The expression of mRNA corresponding to BRMS1, BCL2, BAX, CASP3 and the apoptosis-related X-chromosome RNA binding motif (RBM) genes (RBMX, RBM3, RBM10 small and large variant) was studied by means of differential RT-PCR in 94 samples obtained from previously untreated patients with breast carcinoma. A significant (p=0.03) inverse correlation between BRMS1 mRNA expression and expression of the mRNA corresponding to the large variant of the X-chromosome RBM10 gene was found. The degree of direct correlation with another member of the X-chromosome RBM gene family, RBMX, almost attained statistical significance (p=0.06). These results point towards a possible link between BRMS1 expression and apoptosis in human breast cancer through a relationship with the expression of genes belonging to the X-chromosome RBM family.