Results of chemotherapy trials for small cell lung cancer carried out for the past 5 years were analyzed from view point of dose intensity. Early study of CDDP+EP+ADM (1985 to 1987) showed moderate response rate (RR) of 72% with MST of 369 days. Succeeding alternative protocol of CDDP+EP+VCR/CPM+ADM+MTX (1989-1990) showed improved RR of 88% and MST of 13 months. Actual dose and interval for the alternating regimen was superior to the single arm regimen. Projected relative dose intensity against MAOP protocol including 6 drugs common to our regimen was 0.86 and delivered RDI was 0.61 with comparable RR and MST. The results may indicate that change of dose intensity within the conventional range does not result in major advantage or disadvantage for substantial prolongation of the survival in SCLC patients.