The enzyme phenylalanine decarboxylase () catalyzes the chemical reaction
This enzyme belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is <small>L</small>-phenylalanine carboxy-lyase (phenylethylamine-forming). Other names in common use include <small>L</small>-phenylalanine decarboxylase, aromatic <small>L</small>-amino acid decarboxylase, and <small>L</small>-phenylalanine carboxy-lyase. This enzyme participates in phenylalanine metabolism. It employs one cofactor, pyridoxal phosphate.