Neoadjuvant chemotherapy prior to definitive radical surgery or radiotherapy may be effective in reducing tumor volume or clinical stage and may even enhance pelvic control and survival. However, there are significant limitations to the use of neoadjuvant therapy in the non-responder group. They include delayed total treatment course, the presence of drug resistant clones which result in accelerated tumor growth, and limited bone marrow reserve for subsequent definitive therapy. Thus, there is a need to identify parameters providing a more precise indication of the response to neoadjuvant chemotherapy in patients with invasive cervical cancer. From Jan. 1995 to Jan. 1996, neoadjuvant chemotherapy with 3 courses of cisplatin and vincristine was used in 32 patients with invasive cervical cancer (FIGO stage Ib to IIIb; tumor size greater than 2 cm). Prior to chemotherapy, quantitative tissue levels of epidermal growth factor receptor (EGFR) and c-erbB-2 oncogene protein were measured by using an enzyme-linked immunosorbent assay (ELISA). Tumor size was estimated before and after chemotherapy. Relations between oncoproteins and reductions of tumor size were evaluated. Tumor size prior to neoadjuvant chemotherapy did not show any correlation with either the concentrations of EGFR or c-erbB-2 oncoprotein. As well, the tumor reduction index did not manifest any correlation with EGFR, it did had an inverse linear correlation with the c-erbB-2 oncoprotein levels (Rs = -0.71, P < 0.05). The results of this study suggest that c-erbB-2 oncoprotein is associated with a reduced response to neoadjuvant chemotherapy in primary treatment of invasive cervical cancer and may be useful in directing therapeutic approaches.