Hugh Hefner's son Marston was arrested last night for allegedly attacking his girlfriend Claire Sinclair, the 2011 Playmate of the Year.

The pair share a place in Pasadena, CA, and TMZ reports that one of Sinclair's family members called 911 claiming that Marston had attacked her.

Sinclair reportedly had bruises and red marks on her body, and she told cops that Marston had punched her and kicked her in the stomach, then refused to let her leave the premises.

n his defense, Marston said they'd definitely gotten into an argument, but he would not own up to hitting Sinclair.

Didn't matter though. Cops arrested him for misdemeanor domestic violence.

He was released on $20,000 bail hours later.