The Therapeutic Intervention Scoring System (TISS) has been introduced (Cullen DJ, Civetta JM, Briggs BA, et al: Therapeutic intervention scoring system: A method for quantitative comparison of patient care. Crit Care Med 2:57-60, 1974) at the Massachusetts General Hospital as a means of quantifying the medical and nursing care required by critically ill patients. The method has been instituted in the Intensive Care Unit of Memorial Cancer Center to evaluate its applicability to patients who develop life-threatening complications of their disease or its treatment. This is a preliminary report of the system's use in 55 consecutive patients who averaged 33.4 intervention points per day. This average compares closely with that of postcardiac surgery patients (31.8 points), the group that required the most care of all patients in the initial study. The results indicate the usefulness of this sytem in evaluating severity of illness, predicting survival, and assessing cost benefits. It has proven to be a simple and accurate method of assessment when simple and accurate method of assessment when applied to this patient population, but certain modifications seem warranted and have been suggested herein.