In a study of decisions not to treat febrile patients, we reviewed the medical records of 1256 people admitted to nine extended-care facilities in Seattle during 1973. Fever, defined as two temperatures of 38.33 degrees C to 38.83 degrees C (101 to 101.9 degrees F), within 24 hours or one temperature greater than or equal to 38.88 degrees C (102 degrees F), developed in 190 patients before two years of stay. Active treatment, defined as antibiotics or hospitalization (or both), was ordered for fever in 109 patients, of whom 10 (9 per cent) died. Active treatment was not ordered for 81 patients, of whom 48 (59 per cent) died. The pre-decision factors that showed a significant relation (P less than 0.05) to such nontreatment were: diagnosis, mental status, mobility, pain, narcotics prescribed, size of the facility, relation of the physician to the patient and medical-record statements documenting the patient's deterioration or plans for nontreatment in general. This pattern of nontreatment suggests that physicians and nurses did not intend to treat these patients actively and that high mortality was expected.