The aim of this study was to examine the correlation between intratumoral microvessel density (iMVD) and the presence of cellular fibronectin isoforms, ED-A and ED-B, in order to identify those tumours with a prominent angiogenic phenotype. 91 cases of invasive ductal breast carcinoma were evaluated for TNM, histological grading, percentage of Ki-67+ cells and receptor hormonal status. iMVD was determined as a single microvessel count in a 200 x microscope field from the region of the tumour that appeared to be most densely vascular. When the mean values of iMVD of the various groups were compared, no significant difference was noted (Mann-Whitney test). When tumours were classified as high or low iMVD, based on a cut-off value (99 vessels/0.74 mm2), cases with high iMVD were significantly more numerous in poorly differentiated G3 tumours (P = 0.01, Chi-square test), and in tumours with lymph node metastasis (N0 versus N1 + N2; P = 0.002). The possibility that high iMVD was the expression of prominent vascular neoformation was explored using ED-A and ED-B isoforms of fibronectin as markers of neoformed vessels. ED-A + and/or ED-B + blood vessels were < 10% of total vessels, were detected in approximately 50% of cases independently of iMVD values, and were not more numerous in tumour areas with hot spot vascularisation. Our findings indicate that iMVD and expression of ED-A/ED-B reflect different aspects of tumour-associated angiogenesis.