The exact causes of acute myeloid leukaemia are unknown and in most cases it is unclear why leukaemia has developed. Research into possible causes is going on all the time.

Large doses of radiation may increase the risk of leukaemia. People exposed to high levels of radiation, such as nuclear industry accidents, have a higher risk of developing leukaemia than people who have not been exposed to radiation.

Smoking increases the risk of developing AML. It is thought that this may be due to the concentrated levels of benzene in cigarette smoke. In very rare cases, AML may occur after long-term exposure to benzene (and possibly other solvents) used in industry.

Rarely, some anti-cancer treatments such as chemotherapy or radiotherapy can cause leukaemia to develop some years later. The risk is increased when certain types of chemotherapy drugs are combined with radiotherapy. When leukaemia develops because of previous anti-cancer treatment this is called secondary leukaemia or treatment-related leukaemia.

People with certain blood disorders, such as myelodysplasia, or some genetic disorders, including Down's syndrome, have a higher risk of developing AML. It is not caused by an inherited faulty gene.

Acute myeloid leukaemia isn't infectious and can’t be passed on to other people.