The 79-year-old was last seen in the High Street area of Navenby at around 9.50am today.
It is believed she may have caught the bus to Lincoln from a bus stop opposite the café in Navenby. Marion may have got off the bus at any location between Navenby and Lincoln.
She was wearing a dark green coat, green trousers and black shoes.
She was carrying a grey coloured handbag.
If you have seen Marion please call police on 101, quoting incident number 95 of March 5.