Angiogenesis contributes to the growth and secondary spreading of solid tumors. Platelet-derived endothelial cell growth factor (PD-ECGF)/thymidine phosphorylase (TP) has been identified as such an angiogenic factor. In this study, the expression of PD-ECGF/TP and VEGF was evaluated by immunohistochemical staining of tumor specimens from 40 patients with cervical intraepithelial neoplasia (10 with moderate dysplasia; 10 with severe dysplasia; 10 with carcinoma in situ; 10 with invasive carcinoma). The microvessel density was assessed by immunostaining for factor VIII-related antigen in the most highly neovascularized area. In both the nucleus and cytoplasm, the intensity of PD-ECGF/TP expression in carcinoma in situ and invasive carcinoma was significantly stronger than that in moderate dysplasia. However, the intensity of VEGF expression was not significantly different in the various specimens. The microvessel density in mild dysplasia was significantly different from that in carcinoma in situ (p<0.05), and that in invasive carcinoma (p<0.05). There was no significant relationship between the microvessel density and the expression of PD-ECGF/TP or that of VEGF. These results show that the expression of PD-ECGF/TP appears to be involved in the promotion of angiogenesis in cervical intraepithelial neoplasia.