Kimberley Richmond, also known as Kimberley Barker, aged 31, was last seen in the early hours of this morning at Leeds General Infirmary.
She is described as white, with straight blonde hair, 5ft tall and slim.
She was last seen wearing a cream-coloured gown, black cropped trousers, brown short boots and was carrying a black handbag.
She is known to the West Park and Armley areas of Leeds.
Anyone with information can call police on 101, quoting log 130 of November 26.