The fifth Republican presidential primary debate of the campaign drew 18 million total viewers for CNN, down 5 million from the audience that watched CNN's first debate in September.
Still, 18 million viewers made the Tuesday night debate the second most-watched program in CNN's programming history, the network said in a release. The September debate, which drew 23 million people, was the network's best rating event ever.
GOP debates this election have proven to be a ratings generator, largely due to the unpredictability factor with billionaire businessman Donald Trump on the stage.
In August, Fox News hosted its own GOP debate and got 24 million viewers.