Pretreatment performance status (PS)is a major prognostic factor for both treatment response and survival duration in cancer clinical trials. PS is, however, a subjective index that may be markedly influenced by acute self-limited events. The objective of this study was to develop a prognostic index, based on pretreatment laboratory results, that might serve as an alternative to PS in patients with small cell anaplastic lung cancer. Results have been analyzed in 56 newly diagnosed patients with a minimum followup of 10 months and a median followup of 21 months. Patients were divided into high and low groups for each laboratory parameter based on readings either above or below the median value. Patients with high hemoglobin or albumin levels or low serum alpha-1 globulins, gamma globulins, or LDH survived significantly longer than patients with the opposite levels. When these factors were evaluated by multivariate analysis, albumin and hemoglobin were the most influential prognostic factors for survival. After inclusion of these two laboratory parameters, PS was no longer a significant prognosticator of survival. An objective prognostic index based on pretreatment laboratory results appears feasible in patients with small cell lung cancer.