Cameron Douglas entered the plea Wednesday in Manhattan federal court. The son of the Oscar-winning actor was arrested in July 2009 at a Manhattan hotel.
He was originally put under house arrest. But he was thrown in jail after his girlfriend allegedly tried to smuggle heroin to him in an electric toothbrush.
Douglas has acted in movies including 2003's "It Runs in the Family," starring his father and grandfather, Kirk Douglas.
He faces a minimum 10 years in prison.
