It has been difficult to compare the impact of different dosing practices in treatment programs. Hryniuk and colleagues retrospectively analyzed treatment outcome in a number of different tumors as a function of what they have termed dose intensity. They defined dose intensity as the amount of drug delivery per unit of time, expressed as mg/m2/wk, regardless of the schedule or route of administration. Relative dose intensity (RDI) is the amount of drug delivered per unit of time relative to an arbitrarily chosen standard single drug, or, for a combination regimen. Calculation of the dose intensity, therefore, require the assumption that differences in scheduling dose not influence treatment outcome. Retrospective reviews of the clinical literature indicate that dose intensity of single agent or combination chemotherapy correlates well with outcome in cancer of the breast, lung, ovary colon, or lymphoma. To confirm adequately the data obtained from retrospective review prospective randomized trials are required to determine whether dose (dose intensity) is independent determinant of outcome. In this paper prospective trials of dose intensity were reviewed and some of them in breast cancer, small cell lung cancer, ovarial cancer, malignant lymphoma, or germ cell tumor showed correlation between dose intensity and single anticancer agent regimens or combination regimens. High dose chemotherapy with supportive therapy such as administration of hematopoietic growth factor, autologous bone marrow transplantation, or peripheral blood stem cell transfusion, was also reviewed. Some of these modality showed the suggestive correlation between these therapeutic intensification and the prolongation of survival rate. Intensive chemotherapy for curable intent should be investigated very carefully in near future.