Aldolase B is an isoenzyme of fructose 1,6-bisphosphate aldolase (aldolase A), which is also capable of cleaving fructose 1-phosphate to form glyceraldehyde and dihydroxyacetone phosphate (DHAP). The reaction is reversible. Also known as Aldolase (Class I), it is found in the liver and kidney.

Fructose-1,6-bisphosphate aldolase (EC 4.1.2.13 ) is a tetrameric glycolytic enzyme that catalyzes the reversible conversion of fructose-1,6-bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. Vertebrates have 3 aldolase isozymes which are distinguished by their electrophoretic and catalytic properties. Defects of aldolase B cause fructose 1-phosphate to accumulate in tissues which contain fructokinase, a condition known as hereditary fructose intolerance.