The aim of this study was to evaluate the prognostic value of preoperative concentrations of the serum markers of type I collagen synthesis (PINP, PICP) and degradation (ICTP) in breast cancer. One hundred and eighty-four breast cancer patients without advanced disease were enrolled. Preoperative serum markers of type I collagen were assessed with specific radioimmunoassays. Elevated preoperative serum concentrations of ICTP (>4.9 microg/l) correlated statistically significantly with a poor prognosis for the breast cancer (P=0.0004) and shorter disease-free survival (P=0.02), and multivariate regression analysis likewise showed an elevated ICTP concentration (P=0.008), high grade (P=0.03) and high pathological stage (P=0.02) to be risk factors for poor survival. Sixty-five out of the 184 patients developed metastatic disease during the follow-up. The median follow-up time was 62 months (range 6-111 months). High ICTP (P=0.02) and large numbers of metastatic nodules (P=0.002) were prognostic factors for shorter disease-free survival in multivariate regression analysis. PINP and PICP had no significant prognostic value with respect to either overall or disease-free survival in this analysis. Our results indicate that preoperatively elevated serum ICTP is a prognostic factor in breast cancer, the measurement of which should improve the accuracy of predictions of the clinical outcome.