The prognostic significance of planned and unplanned gaps in radiotherapy and chemotherapy for limited-disease small-cell lung cancer (LD-SCLC) has been retrospectively evaluated in a series of 245 patients. All of them had cisplatine-based chemotherapy and fractionated radiotherapy. There was substantial heterogeneity in overall radiation treatment time and dose-intensity of chemotherapy attributable mostly to planned and unplanned gaps in therapy. Several variables that potentially may influence survival of the patients after treatment, including duration of treatment gaps, and dose-intensity of chemotherapy and radiotherapy were analyzed using univariate and multivariate Cox regression model. The following variables had significant and independent negative influence on survival in a multivariate model: performance status ZUBROD > 0 (p < 0.0001), metastases to supraclavicular nodes (p = 0.001), dyspnoea according to Borg scale > 2 (p = 0.004) and the average dose intensity of radiotherapy < 80 percent (p = 0.02). An independent association between total dose and survival also has been found. The dose-intensity of chemotherapy did not appear to significantly influence survival. While due to the retrospective character of the present research, this conclusion must be regarded as hypothesis-generating only, we assume that within the range of doses and dose-intensitites used in the present group the preventable gaps in radiotherapy and undue reduction of total radiation dose should be promptly avoided, while gaps in chemotherapy can be deemed acceptable if crucially demanded by the tolerance of treatment.