A few decades ago, the chances of survival for patients with a haematological malignancy needing Intensive Care Unit (ICU) support were minimal. As a consequence, ICU admission policy was cautious. We hypothesized that the long-term outcome of patients with a haematological malignancy admitted to the ICU has improved in recent years. Furthermore, our objective was to evaluate the predictive value of the Acute Physiology and Chronic Health Evaluation (APACHE) II score. A total of 1095 patients from 5 Dutch university hospitals were included from 2003 until 2015. We studied the prevalence of patients' characteristics over time. By using annual odds ratios, we analysed which patients' characteristics could have had influenced possible trends in time. A approximated mortality rate was compared with the ICU mortality rate, to study the predictive value of the APACHE II score. Overall one-year mortality was 62%. The annual decrease in one-year mortality was 7%, whereas the APACHE II score increased over time. Decreased mortality rates were particularly observed in high-risk patients (acute myeloid leukaemia, old age, low platelet count, bleeding as admission reason and need for mechanical ventilation within 24 h of ICU admission). Furthermore, the APACHE II score overestimates mortality in this patient category.