Objectives: To determine the frequency and causes of delayed emergency department presentation in critically ill patients who did not have acute myocardial infarction and to evaluate whether factors such as age, gender, prior medical advice, lack of insurance, or low educational level are associated with delayed presentation., Design: Prospective, descriptive analysis., Setting: Emergency department and medical intensive care unit of an urban county hospital., Patients: All adult patients admitted from the emergency department to the medical intensive care unit for reasons other than unstable angina, acute myocardial infarction, or stroke over two 9-wk blocks., Interventions: Within 72 hrs of intensive care unit admission, patients or their families were interviewed to determine time elapsed between the onset of symptoms and patient emergency department presentation and to elicit reasons for delays in seeking medical treatment., Measurements and Main Results: We interviewed 155 of 173 (90%) of eligible patients and found that 58% waited >24 hrs before presenting to the emergency department. The most commonly cited primary reason for delays were beliefs that symptoms were not serious enough for emergency care (31%) and that symptoms would resolve spontaneously (29%). Most (55%) sought medical treatment only at the urging of family members or other advocates. Although variables such as lack of insurance and low educational level were not associated with delayed presentation, male gender and having sought medical advice before presenting to the emergency department were significantly associated with delay (p =.036 for each)., Conclusions: Because of poor understanding of the gravity and natural progression of their symptoms, most critically ill patients waited >24 hrs to present to our emergency department. Education on warning symptom recognition for serious illnesses may be warranted not only for patients themselves but also for family members and caregivers.