Montel Williams was cited for packing a marijuana pipe at the airport in Milwaukee today ... according to the Milwaukee County Sheriff's Office.
Cops say TSA busted the former talk show host with a metal pipe commonly used to smoke marijuana ... as he went through security.
The pipe -- which was in his carry-on -- set off a metal detector. We're told there was no residue.
Montel is a long time advocate of medical marijuana -- which he uses to manage pain related to multiple sclerosis.
Montel was released after paying a $484 citation for possession of drug paraphernalia. The sheriff's department tells us Montel was very mellow cooperative.