Tony Iommi says Black Sabbath’s hit single “Paranoid” had an unexpected impact on their career.

He'd quickly thrown it together, after being told the band didn’t have enough songs for their second album. “Everybody had gone for lunch,” Iommi tells Planet Rock Radio (audio below). “I stayed in the studio and came up with the riff for ‘Paranoid,’ and I waited for them to come back and said, ‘We need another song.’ They went, ‘Oh, no.’ I said, ‘Yeah, but I got this idea,’ and I played it to them.

“We put it down, recorded it, and that was it,” Iommi admits. “Basically, ‘Paranoid’ was a filler. It was done as a filler. We had never done a three-minute song before … and it's amazing what it did.”

They ended up using “Paranoid” as the title for Black Sabbath's sophomore LP, then watched as it soared into the U.K. Top 5 in 1970.

“The only thing in them days for us with ‘Paranoid’ was it attracted a different audience to what we were used to,” Iommi says. “We saw a lot of screaming girls and things, which we weren't used to at the gigs. And we were doing [the U.K. TV show] Top of the Pops and stuff like that. It was attracting a different audience to what we were expecting, and people would come in to hear the band play, who didn't know us.

“They only heard ‘Paranoid’ on TV and thought, ‘Well, let's go and see them,’” Iommi adds. “And of course, they ended hearing ‘Iron Man’ and all of the rest and thought, ‘Oh my God, what's all of this?’”

Listen to Tony Iommi on Planet Rock Radio

Black Sabbath Albums Ranked

From Ozzy to Dio and beyond, we look at all of the band's studio LPs.

You Think You Know Black Sabbath?