The rehabilitation of James Packer has begun in earnest with the billionaire checking himself into a psychiatric hospital in Boston just days after resigning from the board of Crown Resorts due to mental health issues.

Mr Packer was photographed entering The Pavilion wing of the McLean Hospital, a $5000 a night, 11 bed facility on the outskirts of Boston. He was accompanied by his mother Roslyn Packer, and one of his close business associates, Guy Jalland.

James Packer, who is known to have suffered from depression, has just emerged from a particularly traumatic patch in recent times. Credit:AAP

McLean is described as one of the top psychiatric hospitals in the US, with a list of patients that has included Nobel prize winning mathematician John Nash - whose struggle with mental illness was depicted in the film A Beautiful Mind - and novelist Sylvia Plath.