Acute leukemia or acute leukaemia is a family of serious medical conditions relating to an original diagnosis of leukemia.

In most cases, these can be classified according to the lineage, myeloid or lymphoid, of the malignant cells that grow uncontrolled, but some are mixed and for those such an assignment is not possible.

[1] Forms of acute leukemia include: Based on data from United States Cancer Statistics (USCS) Public Use Database for 2001–2017, the 2021 estimate for new cases of AML and ALL are following:[9] Based on these estimates, AML is about 78% of the total cases.