Assessing clinical significance of apnea exceeding fifteen seconds with event recording. Using event recording, we determined how often apnea exceeding 15 seconds in duration was associated with bradycardia and how often patients with apnea resumed breathing spontaneously. Of 1306 documented apnea events exceeding 15 seconds (54 patients), 926 lasted 16 to 20 seconds, 262 lasted 21 to 25 seconds, and 118 exceeded 25 seconds. Of these episodes, 75.3% were isolated and 14.9% were associated with pulse deceleration, 4.4% with irregular transthoracic impedance, and 5.4% with bradycardia. Event recording provided data supporting discontinuation of monitoring in 50 of 54 patients: 36 spontaneously resumed breathing before the auditory alarm and 14 had a decreased incidence of apnea with maturation. Follow-up of 51 patients (three not located) showed that none had subsequent apparent life-threatening events or sudden infant death syndrome. Our results in these older infants and children (median age 6.7 months) provide substantiation that such patients with apnea of less than 20 seconds without bradycardia do not require continued monitoring. Further, these data suggest that in selected older infants, longer isolated apnea may be well tolerated; however, hemoglobin saturation during sleep and the ability to resume breathing after the apnea alarm delay is prolonged should be verified. Our patient population had a wide age range and heterogeneity of diagnoses, and was typically free of symptoms, so these results should not be extrapolated uncritically to premature infants, infants with chronic lung disease, and patients with symptomatic apnea. 