The USA and the UK have differed substantially in approaches to health care and especially in intensive care provision. We have compared the health care systems, clinical justification for intensive care, selection of patients likely to benefit from such care, and the performance of the systems. The differences are lessening. Both countries are moving away from clinical autonomy as the driving force of medical decision-making. There is increasing recognition that not all patients will benefit from intensive care and that the doctor's obligation to the patient can be limited by constraints set by society.