Andy Myers was sent off as Brentford's troublesome away form continued in Milton Keynes.
Brentford were searching for just their second away win of the season but their hopes took a turn for the worse when Myers was sent off in the first half.
The former Chelsea defender had already picked up a yellow card before he clattered into MK Dons forward Wade Small on 34 minutes - and referee Paul Danson did not hesitate before giving him his marching orders.
The incident was the talking point of the opening period.
There were few chances in the opening 15 minutes, although Brentford's Jay Tabb and Steve Hunt were combining well to try and open up the Dons defence.
Isaiah Rankin had the first real shot of the afternoon after 20 minutes. Strike partner Deon Burton did well to set up the opening but Rankin's strike was easily saved.
MK Dons were keeping possession well but were struggling to create any chances.
On 29 minutes Shola Oyedele almost gifted the visitors the lead. The Dons defender played a mis-placed pass across his own penalty box where Tabb teed up Hunt - only for the midfielder to curl his effort high and wide of goal.
Five minutes later Myers received his second booking and headed for an early shower, while the Dons' Gary Smith was forced off through injury after an earlier challenge by the Bees defender.
Soon after Steve Palmer hit a weak shot for the home side which failed to trouble Stuart Nelson in the Brentford goal.
After the break the match started slowly but Alex Tapp could have grabbed a goal on 56 minutes only for Nelson to make a brave save.
Ten minutes later the home side almost went ahead in spectacular fashion. Ben Chorley hammered a drive from 30 yards but his effort flew just wide.
Dean Lewington and Richard Pacquette had further chances to put Stuart Murdoch's team in front as they tried to take advantage of their extra man.
Small dragged a shot wide in the dying minutes but perhaps Brentford will be relieved to have gained a point after playing almost an hour with ten men.