The humorous and rather bizarre footage shows the man nonchalantly brushing his teeth as if doing so on a train is entirely normal.
The man, who sits on a Northern Line train, scrubs furiously as another commuter sits down next to him before the person filming the video focuses on his toothpaste instead.
Writing online the video maker said: 'I found this man brushing his teeth today whilst commuting on a London tube. As soon as he left, everyone burst out laughing.'
It is unclear whether the footage is genuine or whether it is part of a marketing stunt.
Watch the video below.