Clinical observations indicate that the utility of classical prognostic factors in the assessment of probability of disease free or overall survival of lung cancer patients is not completely satisfactory. This is the cause for search of indices which results would contribute to optimization of this estimation. Of potential value in this aspect may also be the results of laboratory determinations which characterize patient's performance status. Dependencies between the times of overall survival in respect to chosen hematological and biochemical factors from the pretreatment period were analyzed in a group of 233 patients with lung cancer (adenocarcinoma - 44, squamous cell lung cancer - 156, small cell lung cancer - 33 patients) in different stages of disease. Apart from stage of disease and histological type of tumor, independent prognostic factors turned out to be the actual ideal body mass ratio and the number of leucocytes. In patients with less advanced stages of disease, such independent factors, apart from histological type are alpha-1 globulin and gamma globulin.