5-hydroxy-L-tryptophan is the L-enantiomer of 5-hydroxytryptophan. It has a role as a human metabolite, a plant metabolite and a mouse metabolite. It is a 5-hydroxytryptophan, a hydroxy-L-tryptophan and a non-proteinogenic L-alpha-amino acid. It is an enantiomer of a 5-hydroxy-D-tryptophan. It is a tautomer of a 5-hydroxy-L-tryptophan zwitterion.