To determine whether limits to life-sustaining care are becoming more common, we attempted to quantify the incidence of recommendations to withhold or withdraw life support from critically ill patients, to describe how patients respond to these recommendations, and to examine how conflicts over these recommendations are resolved. In 1992 and 1993 we prospectively enrolled 179 consecutive patients from two intensive care units (ICUs) for whom a recommendation was made to withhold or withdraw life support. Where possible, we compared results with data collected in the same units over a similar time period in 1987 and 1988. Recommendations to withhold or withdraw life support preceded 179 of 200 deaths (90%) in 1992 and 1993, compared with 114 of 224 deaths (51%) in 1987 and 1988 (chi2 = 73.76, p < 0.001]. Cardiopulmonary resuscitation was initiated in 10% of deaths in 1992 and 1993 as compared with 49% in 1987 and 1988. Ninety percent of patients agreed within less than 5 d, and only eight patients (4%) refused physicians' recommendations to limit life support. In cases of conflict, physicians in 1992 and 1993 deferred to patients with one exception: physicians were willing to refuse surrogate requests for resuscitation of patients they considered hopelessly ill. We conclude that 90% of patients who die in these ICUs now do so following a decision to limit therapy, that this represents a major change in practice in these institutions over a period of 5 yr, that most patients and surrogates accept an appropriate recommendation to withhold or withdraw life support, and that physicians will refuse surrogate requests in certain circumstances.