A retrospective analysis of various characteristics in 81 small cell lung cancer patients treated at the Mount Sinai Medical Center, New York, from 1974 to 1982 was carried out to identify factors which had prognostic significance for long-term survival, defined as actual disease-free survival for at least 5 years from initiation of therapy. Six patients, five female patients (16.7%) and one male patient (2%), including four limited disease (9.7%) and two extensive disease patients (5%) were long-term survivors (73 to 96+ months from onset of therapy), and among them three remain alive and disease-free at 84, 84, and 96 months from first treatment, respectively. Although several factors, including sex, stage of disease (limited versus extensive), and occurrence of herpes zoster predicted overall survival duration, female sex and an occurrence of herpes zoster were the only variables which were statistically significantly related to 5-year survival. Herpes zoster was a relatively late occurrence whereas female sex was an independent positive prognostic factor.