There are few reports analyzing the results of intensive care for children. We evaluated quantitatively the amount of care required in our multidisciplinary pediatric ICU using the Therapeutic Intervention Scoring System (TISS) and assessed qualitatively the severity of illness using the Clinical Classification System (CCS). Over a 6-month period, there were 323 patients (99 CCS Class II, 83 Class III, 141 Class IV) whose overall mortality at 1-month follow-up was 10% (Class II, 0%; Class III 2%; Class IV, 23%). A strong association was obtained between CCS and TISS admission scores (Class II-TISS, 11 +/- 0.6; Class III-TISS, 20 +/- 0.8; Class IV-TISS, 38 +/- 1.0). Class IV patients had a highly significant difference between survivors (S) and nonsurvivors (NS) for admission TISS (S = 36, NS = 47, p less than 0.001) and highest TISS (S = 38, NS = 54, p less than 0.001), as well as slopes of the regression of TISS points versus days of care (S = -4.2 vs. NS = +2.3). The mortality of our Class IV patients was lower than a comparable adult population with similar TISS scores; however, the TISS regression slopes for Class IV patients were similar. We conclude that CCS and TISS are both useful for describing the pediatric intensive care patient population. TISS is particularly helpful in assessing the amount of care received as well as providing a means of evaluating severity of illness.