Hysteria is the fourth studio album by English hard rock band Def Leppard, released on 3 August 1987 through Mercury Records and reissued on 1 January 2000. It is the band's best-selling album to date, selling over 25 million copies worldwide, including 12 million in the US, and spawning seven hit singles. The album charted at #1 on both the Billboard 200 and the UK Albums Chart.