Objective To explore the clinical characteristics and management of children who were critically ill with severe pertussis and those who had severe pertussis-like syndrome. Methods The patients with severe pertussis and severe pertussis-like syndrome admitted to Pediatric Intensive Care Unit from Mar.2005 to Mar.2013 were involved in this study, and their clinical characteristics were collected and the experience of management was summarized. Results Totally 31 patients were involved in the study, 15 cases were male and 16 cases were female, the median age was 2.68 months(age ranged 34 days-7 months). All the 16 cases of severe pertussis were less than 3 months, and none of them had received pertussis vaccine.Of 31 patients, 16(51.61%) cases were characterized by apnea, 12(38.70%) cases showed cyanosis, 10(32.26%) cases exhibited bradycardia, 8(25.80%) cases presented spasmodic cough, leukocytosis[white blood cell count (26.85± 12.43)×109/L]as well as lymphocytosis[blood lymphocyte(70.10±8.82)%] were observed.Complications included respiratory failure(13 cases, 41.94%), pulmonary hypertension(7 cases, 22.58%), circulatory dysfunction(6 cases, 19.35%) and encephalopathy(5 cases, 16.13%). Two cases of severe pertussis patients presenting with cardiac arrest received CPR survival due to prolonged apnea.Severe pertussis infants were more likely to present apnea, cyanosis, bradycardia and be complicated with pulmonary hypertension than those who had severe pertussis-like syndrome infants [75.00%(12/16 cases) vs 26.70%(4/15 cases), χ2=7.008, P=0.008; 62.50%(10/16 cases)vs 13.30%(2/15 cases), χ2=7.634, P=0.006; 50.00%(8/16 cases) vs 13.30%(2/15 cases), χ2=4.610, P=0.032; 37.50%(6/16 cases) vs 6.67%(1/15 cases), χ2=4.074, P=0.044]. In the patients with pulmonary hypertension group, the white blood cell count, the rate of suffering from respiratory failure as well as circulatory dysfunction, the rate of using mechanical ventilation, the rate of using vasoactive drug were significantly higher than those in the normal pulmonary arterial pressure group[(47.96±17.79) ×109/L vs(23.20±5.29)×109/L, t=2.278, P=0.025; 71.42%(5/7 cases) vs 8.33%(2/24 cases), χ2 =11.943, P=0.001; 71.42%(5/7 cases) vs 8.33%(2/24 cases), χ2=11.943, P=0.001; 42.86%(3/7 cases)vs 0 (0 case), χ2=11.020, P=0.001; 42.86% (3/7 cases) vs 0(0 case), χ2=11.020, P=0.001]. Pertussis-mediated pulmonary hypertension were also treated with milrinone, and all cases were cured. Conclusions Severe pertussis and severe per-tussis-like syndrome in infants are characterized by high morbidity of apnea and respiratory failure.Severe pertussis tends to occur in younger unvaccinated infants(<3 months). Severe pertussis is more likely to be combined with pulmonary hypertension.Pulmonary hypertension is the sign of disease get aggravation, and milrinone treatment may be effective. Key words: Pertussis; Pertussis-like syndrome; Apnea; Respiratory failure; Pulmonary hypertension; Child