The first Lincolnshire derby of the season was a rip-roaring affair which ended all square.
It was a point Boston would have settled for beforehand while Grimsby were happy to come from behind to snatch their equaliser.
The Mariners, beaten on the opening day at Darlington, got off to the worst of starts. They were down to ten men with big defender Robert Jones off injured when Boston struck after nine minutes.
When a throw-in was not cleared Lee Beevers crossed from the right and midfielder Steve Melton looped home a header from 12 yards.
This set-back rocked Grimsby for a spell but they came back strongly before half-time with striker Ashley Sestanovich on form.
Boston were happy to go in a goal to the good but Grimsby came out for the second half with all guns blazing.
Grimsby threw everything at their neighbours, who they were meeting for the first time in a league match.
Boston keeper Nathan Abbey made two great saves to deny Grimsby striker Andy Parkinson but a substitution by Mariners boss Russell Slade paid off.
Striker Michael Reddy had only been on the field for two minutes when he took a through ball by Sestanovich and knocked it past the keeper before scoring from an acute angle.
With 20 minutes left Grimsby believed they could win it but Boston dug deep and maintained their unbeaten start.
A big crowd of 6,737 - topped only once last season at Blundell Park - tried to roar Grimsby home but at least they earned their first point of the season.
Both managers were pleased with the outcome.
Boston boss Steve Evans admitted he would have taken a point beforehand and while Grimsby's Russell Slade was upset not to open his account with three points he took several positives out of the game.
Russell Slade said: "Our performance grew in stature and we dominated for long periods. But for an inspired display by their keeper we could quite easily have won the game." He admitted Boston's early goal shook his team but he added: "I told them at half-time to keepr believing and the result would come." Boston boss Steve Evans said: "For the first 45 minutes we controlled the game. The second half was a different story and with the great atmosphere at Blundell Park the crowd are a 12th man to the team.
"Looking from outside Grimsby have had two bad seasons but the board have backed Russell Slade with the quality of his signings." Steve Evans went on: " We stood strong to get the points and it was good to have Gazza with us watching from the stand. With his illness he has lost nine or ten pounds but trained earlier in the day."