Not sure how many episodes there were, but it appears the concept is guest stars join a pipe smoking Hugh Heffner surrounded by a diverse (yes, very much ahead of its time!) bevvy of beauties and swinging 60s gentlemen...
The story of when the Grateful Dead appeared on the show has become the stuff of legend...
"As the legend goes, the Dead’s sound engineer/LSD chemist Owsley “Bear” Stanley slipped some of his homemade psychedelic concoction into the Playboy After Dark crew’s coffee supply, effectively dosing the entire staff for the late-night program."