The medical photograph was taken at a Florida hospital in 1954 when the Some Like It Hot actress was being treated for womb condition endometriosis.
The X-ray, which shows the star's ribs as well as the outline of her famed cleavage, was printed with her married name DiMaggio - at the time she was going through a divorce from baseball legend Joe DiMaggio.
The bizarre lot is one of many Monroe-linked items up for sale at a Las Vegas auction slated for June (10). The couch the star used during therapy sessions is also expected to sell.
The sale by Julien's Auctions will take place on 26 and 27 June (10) at the Planet Hollywood Resort and Casino in Las Vegas.