5-hydroxyfuranocoumarin 5-O-methyltransferase (, furanocoumarin 5-methyltransferase, furanocoumarin 5-O-methyltransferase, bergaptol 5-O-methyltransferase, bergaptol O-methyltransferase, bergaptol methyltransferase, S-adenosyl-L-methionine:bergaptol O-methyltransferase, BMT, S-adenosyl-L-methionine:5-hydroxyfuranocoumarin 5.1-O-methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:5-hydroxyfurocoumarin 5-O-methyltransferase. This enzyme catalyses the following chemical reaction
The enzyme methylates the 5-hydroxy group of some hydroxy- and methylcoumarins, such as 5-hydroxyxanthotoxin.