Background: We studided the etiologies of mortality in childhood 
Acute Lymphoblastic Leukaemia (ALL) patients at Paediatric 
Oncology Department of St Aliasghar Hospital. 
Methods: In our hospital, between years of 2005 to 2012, we had 
442 registered cases of ALL whose data was collected and analyzed 
regarding to different factors including their age, sex, WBC count, 
immune phenotype, treatment response and timing of death and the 
etiologies of their mortality. 
Results: Among the new registered cases of ALL in the study 
period, 80 (18%) died. Infection was accountable for deaths in 58 
(72.5%) cases. Septicemia, pulmonary infections were documented 
in 41 (51.25%), and 12 (15%) cases respectively. Eleven (13.8%) 
died due to haemorrhage. 
Conclusion: Infection was the chief etiology of mortality in our 
ALL patients. For improving survival it is very important to 
advance our supportive care particularly prevention and treatment 
of infection. By studying mortality causes in clinical and 
demographic subgroups, one gains insights into development of 
strategies and interventions to modify treatment to decrease 
mortality.