The CD44 variant exon 6 sequence is associated with metastasizing clones of rat pancreatic and mammary carcinoma. In human breast and colorectal carcinoma epitopes on the cell surface encoded by exon v6 have been shown to predict poor chances of survival. Breast cancers in 55 patients whose clinical follow-up was available for 6 to 8 years were immunophenotyped for the presence of the CD44 exon v6 epitope and the results were correlated with survival. There was a difference in survival in the first 2.5 years following surgery: of the eight patients with negative tumours none had died during this period. The advantage of the negative group faded at later time points. However, the log-rank analysis revealed that differences between CD44 exon v6-negative and -positive groups were just below statistical significance. Studies with a larger number of patients are needed to establish the role of this CD44 variant as an early prognostic indicator in metastatic dissemination of breast cancer.