Monobenzyl phthalate (MBzP) also known as 1,2-Benzenedicarboxylic acid, 1-(phenylmethyl) ester is an organic compound with the condensed structural formula C<sub>6</sub>H<sub>5</sub>CH<sub>2</sub>OOCC<sub>6</sub>H<sub>4</sub>COOH. It is the major metabolite of butyl benzyl phthalate(BBP), a common plasticizer. BBP can also be metabolized into monobutyl phthalate (MBP). Like many phthalates, BBP has attracted attention as a potential endocrine disruptor.