The exact causes of ALL have not been completely demonstrated, though certain risk factors have been shown to predispose patients to the disease. The risk factors associated with ALL are:

• Age:This disease most commonly affects older adults, and incidence of the disease increases with age (average age at onset is 70 years). The incidence rate of the disease is higher in men than in women, though the reasons for this remain unknown.
• Exposure to chemicals:Cases of ALL have been seen following prolonged exposure to benzene and other solvents.
• Exposure to radiation:Exposure to high doses of radiation increases the risk of developing ALL. In some cases and in lower proportion, ALL has been related to previous radiotherapy to treat tumors.
• Genetic syndromes: Some syndromes such as Down syndrome and congenital diseases like Fanconi anemia increase the risk of ALL.