To test the feasibility and value of an economic appraisal of intensive care, a retrospective follow-up study was performed in two intensive care units in England. Clinical activity data was extracted from the records of 100 consecutive admissions to each unit and used to cost the care received by each patient during their stay in the units. Outcome was measured in terms of survival and quality of life six months after admission. Mortality at discharge from the units was 25% and 15% rising to 31% and 38% respectively six months after admission. Between one-third and one-half of patients alive at six months reported that their health continued to restrict aspects of their daily activities and one-fifth reported serious disability or distress. Total costs averaged 2,000 pounds and 2,280 pounds, equivalent to 525 pounds and 465 pounds per in-patient day. Poor outcome was associated, though not always significantly, with increased age, severity of illness and increased costs. The small sample size and heterogeneous nature of intensive care prevent firm conclusions being drawn from this study but the results indicate that such investigations are both feasible and potentially rewarding.