It was a result that neither side wanted with Grimsby dropping from second to fourth place in the table and the Shrews needing the three points for their play-off hopes.
It was probably a fair result, although Grimsby had the share of the play. And, but for some poor finishing by much travelled striker Mark Stallard, it could have been much worse for Grimsby.
Three times in the second half Stallard had clear chances, twice being foiled by Grimsby keeper Steve Mildenhall and then heading wide with his best opportunity of all.
Shrewsbury were defending their first half lead giving them by Sagi Burton who headed home at the far post from a Neil Ashton corner.
Both sides had to make substitutions around half time due to injury and Grimsby made a tactical switch on 64 minutes bringing on Junior Mendes for the ineffective Andy Parkinson.
That made a difference for the Mariners who looked livelier and within a minute Grimsby were level.
Midfielder Curtis Woodhouse drove the ball at Steve Hogg and, although the ball seemed to strike him on the hand, it seemed a rather harsh decision. Grimsby have had a terrible time from the penalty spot this season but winger Marc Goodfellow crashed a fine spot-kick high into the net.
After that predictably it was all Grimsby and central defender Rob Jones had a header disallowed for climbing all over his man.
Grimsby pressed and pressed towards the final whistle, but with results elsewhere going against them, they ended the day in fourth place and this means that Monday's visit to Leyton Orient, already a big game, could now be a potential decider.
It was amazingly Grimsby's first draw at Blundell Park since the opening day of the season against Oxford after which they had won 12 and lost seven.