Introduction: Acute life-threatening illnesses are rarely encountered conditions at pediatric medical emergency wards but require fast and adequate management to save patient’s life. The aim of this study was to assess acute life-threatening illnesses epidemiology, outcome and factors associated with death of patients at a university pediatric hospital’s medical emergency department in Morocco. Material and Methods: This cross-sectional observational study of all cases of children aged from 29 days to 15 years admitted for an acute life-threatening illness at Rabat children hospital’s medical emergency room, was carried over a period of one year, from January 1, to December 31, 2014. Results: A total of 183 patients were included, corresponding to 0.3% of all admissions during the same period. The acute life-threatening illness was related to a respiratory disorder in 45.3% of cases, to a hemodynamic disorder in 20.7% of cases, to a neurological disorder in 25.1% of cases and to another disorder in 8.7% of cases. The overall death rate was 44.8%. Acute life-threatening respiratory disorders were more frequent in patients younger than 2 years (p < 0.001), while acute life-threatening illnesses other than respiratory or hemodynamic or neurologic disorders were more frequent in patients over 2 years of age (p = 0.009). Factors associated with death were age less than 2 years (OR = 2.872 (1.528;5.399), p = 0.001). Conclusion: Acute medical life-threatening illnesses in children were unfrequent but were burdened with heavy mortality in this study. Children younger than 2 years were more at risk of death.