Prior non invasive ventilation (NIV) is associated with an increased mortality in patients with haematological malignancies and acute respiratory failure treated by invasive mechanical ventilation (IMV). We have assessed whether NIV failure is an independent prognostic factor for hospital discharge in a general cancer population treated by IMV.106 patients with solid tumors and 58 patients with haematological malignancies were eligible for this retrospective study; 41 were treated by NIV before IMV.The main indications for mechanical ventilation were sepsis/shock (35%), acute respiratory failure (33%), cardiopulmonary resuscitation (16%) and neurologic disease (10%). Respectively, 35%, 28% and 24% of the patients were extubated, discharged from the intensive care unit (ICU) and from the hospital. For patients treated with NIV prior to IMV, the rates were 22%, 17% and 10%, respectively. In multivariate analysis, 3 variables were independently associated with a decreased probability of being discharged from the hospital: NIV use before IMV (odds ratio/OR=0.30, 95% confidence interval/CI: 0.09-0.95; p=0.04); leukopenia (OR=0.21, 95% CI: 0.06-0.77; p=0.02) and serum bilirubin >1.1 mg/dl (OR=0.38, 95% CI: 0.16-0.94; p=0.04).NIV failure before IMV is an independent poor prognostic factor in cancer patients treated by IMV.