Portnoy discovered Zappa as a teenager in the late 1970s. He was attracted by his sense of humor, but beyond funny songs like Broken Hearts Are For Assholes, Crew Slut and Catholic Girls Portnoy was also amazed by Zappa's musicianship and diversity. "From classical to jazz and electronica, nothing seemed beyond the man.. (...) Frank Zappa always had the very best musicians in his band, from Steve Vai to Adrian Belew and Terry Bozzio. I got to see him on his last tour in ’87-’88. I actually followed him around America, and remember sleeping outside The Beacon Theater in New York to get tickets for a show. These days, you just have to click a link online, but back then it was tougher for us fanatics!"
Portnoy also performed during the Zappa Plays Zappa tribute concerts in 2009-2011, even though he was a bit cautious to join in. "There's a few other tributes I'd like to do and now I have some time, who knows. One of my biggest heroes is Frank Zappa and I'd love to do something, but I think the problem is it would be so unbelievably musically intense, I don't know how much fun it would be!
On his personal website Portnoy names Zappa as his greatest musical influence. He cites Joe's Garage Acts I, II & III and the six You Can't Do That On Stage Anymore albums as his favorite Zappa records, but on a page with questions asked by fans he names several more: "I think I mostly lean towards the mid 70's to mid 80's periods as my favorites. Beginning with “Over-Nite Sensation” & “Apostrophe (')” (both classics) up thru “Us And Them.” I especially love “Sheik Yerbouti” and “Joe's Garage” most of all. But also really love Live in New York” and “Tinseltown Rebellion”....and also “One Size Fits All” and “Zoot Allures.” HELL - I LOVE EM ALL!!!! You're best bet is all 6 volumes of “You Can't Do That On Stage Anymore” ...that would be my desert island pick!" When asked what his favorite concept albums are, Portnoy names "Joe's Garage" as one of them. (http://www.mikeportnoy.com/aboutmike/faq/answers/22.aspx)
In an interview for "Classic Rock Magazine" Portnoy talked enthusiastically about Zappa: "He’s my master, my all-time hero. I have his moustache tattooed on my leg. Seriously, my leg is a shrine to my five favourite artists: The Beatles, The Who, Led Zeppelin, Pink Floyd and Zappa. A bit different to wearing your influences on your sleeve, eh?" Portnoy also expressed awe about Zappa's unique accomplishments. "I reckon there’s nobody like him today. Maybe Mike Patton comes close, but even he doesn’t have what Zappa had. Steve Vai also has a certain element of Frank in the way he performs, composes and leads. But then he was taught by the very best, wasn’t he? I never met Frank. But I did get the chance to meet his son Dweezil last year when he was doing his tribute tour to his dad (Zappa Meets Zappa). That was a special moment for me. And I’ve gotten to know Vai and Bozzio quite well over the years, which gives me a flavour of what the great man himself must have been like. Frank Zappa was a genius. Unique and a visionary. There will never be anyone else like him."