We retrospectively reviewed the information in our data base concerning 127 patients with advanced non-small-cell lung cancer. Seventeen pretreatment clinical variables including serum C-reactive protein (CRP) were analyzed to determine the factors related to survival using Cox's proportional hazards model. Univariate analysis revealed that eleven explanatory variables were significant. In multivariate statistical technique for those variables, six were selected as significant factors. The highest hazard ratio was observed in the serum CRP (3.82). The other factors were therapy (2.52), serum lactate dehydrogenase (2.41), serum total protein (2.20), white blood cell counts (1.98) and performance status (1.80). Median survival times estimated by the Kaplan-Meier procedures in patients with normal CRP (CRP < 0.2 mg/dl) and high positive CRP (CRP > or = 3.0 mg/dl) were 24.9 months and 3.7 months, respectively. These results suggest that serum CRP is an independent survival determinant in advanced non-small-cell lung cancer.