Frozen sections of benign and malignant prostate tissue were immunohistologically analysed for ICAM-1, VCAM-1, alpha-4, alpha-5, alpha-L, beta-1, CD44, and E-selectin. The effect of HUVECs on the expression of cell adhesion molecules by PC3 and Dul45 cells investigated. The effect of PC3 and Du145 cells on the expression of cell adhesion molecules by HUVECs was investigated. PC3 and Du145 conditioned medium and endothelial cell-conditioned medium did not induce changes in cell adhesion molecule expression by endothelial, and PC3 / Du145 cells, respectively. The prevalence and level of expression of ICAM-1 in prostate tumours appear to be significantly greater than in their benign counterparts. Co-culture of HUVECs with Du145 cells induced an upregulation of ICAM by the Du145 and a down-regulation in CD44 by HUVECs. Co-culture of PC3 cells with HUVECs induced a down-regulation in CD44 and upregulation of alpha-5 by the PC3 cells. The expression of ICAM-1 by Du145 metastatic prostate cancer cells may be involved in the stabilised attachment of Du145 cells to HUVECs. The expression of CD44 by HUVECs may play a role in the initial attachment of Du145 cells to HUVECs. The expression of CD44 by PC3 prostate cancer cells may be important in the initial attachment of PC3 cells to HUVECs, while 5 may play a role in the stabilised binding and / or transendothelial migration of PC3 cells. Conclusion: ICAM-1 confers an invasive phenotype to prostatic epithelial cells.