The Torchwood star told The Mirror that some of the photos he is sent from his female admirers are "seriously raunchy".
Barrowman said: "Sometimes I get sent knickers and occasionally I get requests to send some of my own underwear back. I always politely decline. It's not going to happen.
"I get sent some seriously raunchy photographs too. They really don't hold back, some of these women. The photographs are filthy."
The 44-year-old actor added: "They're not really my thing to be honest. All I'll say is I appreciate the loyalty. So thank you."
Torchwood: Miracle Day continues this Thursday at 9pm on BBC One, and airs this Friday at 9/8c on Starz in the US.
Watch John Barrowman discuss Torchwood: Miracle Day with Digital Spy below: