The DNA content of 50 breast cancers of varying tumour type, grade and stage was measured using static image cytometry, and correlated with vimentin expression in the tumour cells. A tendency to increased vimentin expression and aneuploidy was observed in high grade and late stage tumours. A statistically significant difference was observed in DNA index and ploidy balance between grade 1 and grades 2 and 3 carcinomas (P < 0.05) and between grade I and stage II carcinomas (P < 0.05). There was a significant difference in the expression of vimentin between grades 1, 2, 3 (P < 0.001), and stages I, II, and III ductal carcinomas (P < 0.05). No significant difference was observed in the proliferation index and the degree of hyperploidy (P > 0.05) Clonal heterogeneity was observed in 25% of breast carcinomas, and was associated with increased vimentin expression. These changes may be indicative of genomic alteration and tumour aggressiveness.