Gillingham dropped more valuable points in their chase for a League 2 play-off place. George Lapslie cancelled out a Grimsby opener scored by Donovan Wilson in the first half.
Connor Mahoney hit the woodwork for the Gills after the break and Shad Ogie blazed a shot over after a good run as the match finished 1-1.
It’s eight unbeaten at home for Gillingham but six of those have been drawn. A sickness bug that hit the Gills ahead of the game kept midfielder Ethan Coleman out while defender Conor Masterson was suspended.
It meant George Lapslie and Robbie McKenzie returning to the starting eleven. Gillingham needed a win to keep their play-off ambitions looking realistic and were up against a side starting the day fourth from bottom, albeit five unbeaten and boasting a win over top-five side MK Dons last time out.