Conflicting results exist regarding the significance of the metastasis suppressor gene nm23-H1 in cancer patients. Initial results from a study done by our group were more indicative of its negative prognostic role in breast cancer. Our aim was to examine further its significance in patients with metastatic breast cancer.With the semi-quantitative Reverse Transcripted-Polymerase Chain Reaction (RT-PCR) method, solid tumor specimens or samples from malignant effusions in breast cancer patients were examined for the nm23-H1 gene. Clinical data were collected retrospectively and gene expression was correlated with survival.Fourteen patients were included in the current analysis. The gene was detected in 7 patients. No statistically significant differences were observed in the comparison done for prognostic factors between nm23-H1-positive and nm23-H1-negative patients. Women in whom the gene was not detected had longer median survival (49 vs. 6 months, p=0.09).In advanced breast cancer, nm23-H1, as detected by RT-PCR, seems to be a predictor of bad prognosis.