Cathryn Holdsworth, 72, from Illingworth, was last seen on Friday, September 8 at Calderdale Royal Hospital.
She had been living in the Illingworth but may have contacts across the Halifax area, West Yorkshire and nationally.
Ms Holdsworth is described as white, around 5ft2ins tall and of medium build.
She has very short speckled, grey hair and dark glasses, and may be wearing a dark green-coloured fleece.
Anyone who has seen or heard from Cathryn, or who knows where she is now is asked to call police via 101 quoting 1520 of September 19.