A series of 76 patients undergoing surgery for primary breast carcinoma has been prospectively studied in order to evaluate the relative weight of nm23-H1 protein expression in disease-free survival. Expression of nm23 protein was immunohistochemically assessed. In all, 39% (29/74) of the turners showed positive staining for nm23-H1 protein expression. Negative nm23-H1 expression was found in poorly differentiated, tumors (p<0.02). There was no significant relationship between nm23-H1 and the other clinicopathological and biological features examined. In the univariate statistical analysis, node positivity, G3 histological grade and high flow cytometric S phase fraction (SPF) value proved to be significantly related to risk of relapse. In the multivariate analysis, only histological grade (G3) and high SPF values (>10.6) proved to be independently related to risk of relapse, with a hazard ratio of 9.84 and 7.98 respectively. Our preliminary study suggests that immunohistochemical nm23-H1 expression should not be considered a marker for predicting tumor progression and patient prognosis.