Background/aim: Cancer patients frequently need intensive care support due to respiratory failure. We aimed to evaluate the predictors of mortality in cancer patients who were admitted to the intensive care unit (ICU). Materials and methods: This study was performed in the ICUs of two centers between 1 January 2008 and 31 December 2015. Demographic data, cancer type, causes of respiratory failure, comorbidities, APACHE II scores, treatments, and mortality rates were recorded. Results: A total number of 583 cancer patients (477 males) were enrolled from the two centers. Of those, 472 patients had lung cancer (81%), while 111 had extrapulmonary malignancies (19%), having similar mortality rates. Causes of respiratory failure were mostly invasion of the cancer itself in 84% of cases and due to infection in 12%. ICU mortality rate was 53% and the 1-year mortality rate was 80%. APACHE II scores were significantly higher in nonsurvivors (P < 0.001). One-year survival was found to be significantly shorter in females than males (9 days vs. 12 days) in patients with lung cancer. Conclusion: Mortality rates of cancer patients who need ICU support are higher than overall ICU mortality. High APACHE II scores and female sex seem to be related to mortality in these patients.