Abstract： Objective To investigate the clinical manifestations and prognostic factors of hospital death in connective tissue disease patients with acute respiratory failure caused by pneumocystis pneumonia (PCP) admitted to two medical intensive care units (MICU).Methods A retrospective review was conducted for all connective tissue disease (CTD) patients with acute respiratory failure from PCP in MICU of 2 academic medical centers between 2010 and 2015.The patients were divided into survivors and non-survivors.Demographic and clinical data,including laboratory,radiological and microbiological findings,as well as therapy,clinical course,mortality and prognostic factors of hospital mortality were included in the analysis.Logistic regression models were used to determine the effect of prognostic factors on hospital death after adjusting for covariates of which the p values were less than 0.1.Results A total of 41 patients with connective tissue disease were identified.The PaO2/FiO2 ratio (PFR) on ICU admission was 120 mmHg (55-180 mmHg,1 mmHg =0.133 kPa).Common clinical features included dyspnea (90.2％,37/41),fever (87.8％,36/41) and dry cough(65.9％,30/41).58.5％ (24/41) and 17.1％ (7/41) patients were co-infected by CMV and aspergillus,respectively.The overall mortality rate was 75.6％ (31/41).Compared with survivors,the age,APACHE Ⅱ score and incidence of barotrauma in non-survivors were higher (39±17 vs 58±15,t =3.018,P=0.002),(15±6 vs 19±5,t =2.528,P=0.019),(0/10 vs 12/31,x2 =5.473,P =0.021),while PFR on ICU admission was lower in non-survivors (172 ± 68 vs 116 ±49,t =-1.893,P =0.007).Logistic analysis showed that PFR on ICU admission was the independent risk factor for hospital death (OR =1.004,95％ CI:1.002-1.006,P =0.048).Conclusions Mortality rate among patients with acute respiratory failure secondary to CTD related PCP is still high,and the poor prognostic factors of hospital mortality included PFR on ICU admission and barotrauma.