It is the first single from the album, while the B-side is the song "The Wizard". It reached number 4 on the UK Singles Chart and number 61 on the Billboard Hot 100. Also, the song topped the German Singles Chart.
"Paranoid" is consistently ranked as one of the greatest heavy metal songs of all time. It is typically associated with both Ozzy Osbourne and Black Sabbath due to its popularity. After Osbourne left the band in 1979 to pursue a solo career, he continued to perform this track normally at the end of the set. Various different live versions have been recorded with Osbourne. This is due to the changes in band lineup since the original Blizzard of Ozz in 1980. Popular live versions featuring various guitarists including Randy Rhoads, Brad Gillis, Jake E. Lee and Zakk Wylde were all recorded and later released.
It was ranked #34 on VH1's 40 Greatest Metal Songs. In March 2005, Q magazine placed it at number 11 in its list of the 100 Greatest Guitar Tracks. Rolling Stone ranked it number 250 on their list of the 500 Greatest Songs of All Time and called the song, "a two-minute blast of protopunk". In 2009, it was named the 4th greatest hard rock song of all time by VH1.