BACKGROUND AND AIM: Modern cancer treatments often come with life-threatening complications, among which one of the most common is infection. This study aims to evaluate the prevalence and outcomes of common infections in critically ill hemato-oncology patients, and to identify any factors associated with these infections. METHOD:This is a retrospective observational study of all children either with a haemato-oncology diagnosis or undergoing hematopoietic stem cell transplantation, who have been admitted to the Hong Kong Children's Hospital Pediatric Intensive Care Unit(PICU) over a one year period. Infection characteristics and patient outcomes were evaluated and compared across different sub-groups. Univariate and multi-variable analyses were employed to identify risk factors associated with the development of active infection. RESULTS:Out of the 124 critically ill hemato-oncology admissions in this investigation, 45(36.3%) admissions were associated with infections, including 31(25%) admissions involving bacterial infections, 26(20.9%) involving viral infections and 6(4.8%) involving fungal infections. The most common site of infection was bloodstream infection. More than half(61.3%) of the bacterial infections were of an antimicrobial resistant phenotype. After adjusting for confounding variables, post hematopoietic stem cell transplantation status (odds ratio,4.48; 95%CI, 1.75-11.45;p=0.002) and neutropenia (odds ratio,2.69;95%CI,1.12-6.47;p=0.027) were found to be significantly associated with clinically significant active infection. CONCLUSIONS:Critically ill hemato-oncological patients are more likely to develop infections in comparison with general PICU patients (Table ), and infections are significantly associated with post hematopoietic stem cell transplant and neutropenic status. Further studies are warranted to identify the underlying root causes and develop prevention strategies to mitigate the likelihood of infection in this patient population.