The latest eviction saw Caroline booted out of the house, with just over 600,000 watching between 9 and 10:30PM.
It's an all time low rating for the series since its start on Channel 4 back in 2000.
The live show went up against the opening ceremony of the 2012 London Olympics, which was watched by an impressive average audience of more than 23 million.
It was the most watched telly show in the UK for almost 20 years, with more than a billion viewers said to be watching across the world.
Big Brother then performed surprisingly well, with fellow Channel 5 show The Bachelor dipping to just 200,000 viewers from 10PM.
Spin off show Big Brother's Bit On The Side managed to attract 230,000 viewers from 11:30PM, as Alice took over for a still sick Emma Willis.