• During a two-year period, ten infants died suddenly and unexpectedly with a home cardiorespiratory monitor available. We investigated the compliance with appropriate monitoring technique as well as the medical and demographic factors associated with these deaths (90% were due to sudden infant death syndrome). At least six and probably eight of these ten families were noncompliant with appropriate monitoring technique. The main comparison group consisted of 211 patients for whom care with home cardiorespiratory monitors was initiated and continued. Bronchopulmonary dysplasia and severe, apparent life-threatening events were significantly increased in the subjects, as were the following characteristics: black race; lack of private medical insurance; unmarried mother; maternal age of less than 25 years; cigarette smoking by mother during pregnancy; and low Apgar scores. These diagnostic and demographic factors may be useful in predicting the infant at highest risk for sudden and unexpected death when a home monitor is prescribed. Noncompliance with proper monitoring technique occurred in a majority of the study patients; methods of educating parents of infants at high risk of sudden infant death syndrome with the necessity for compliance need to be developed.