In order to describe the real biological behavior of the small-cell lung cancer we have analyzed survival rates of 66 patients with small-cell lung cancer who did not receive any specific anti cancer therapy. Also, objective of this study was to evaluate the staging system of the small-cell lung cancer. Untreated small-cell lung cancer patients with limited stage disease had statistically significant (p < 0.05) better survival rates in comparison to patients with extensive stage disease. T and N factor of the TNM classification did not influence the survival in untreated small-cell lung cancer patients. It appears that the TNM staging system is not predicting survival probabilities of untreated patients with small-cell lung cancer, while the two-stage system appeared very well based on survival probabilities of these patients.