The Sickness is the debut studio album by the American heavy metal band Disturbed. The album was recorded in 1999 and released on March 7, 2000. The album peaked at number 29 on the Billboard 200 chart and it has spent a total of 103 weeks on that chart, as of June 2010.The Sickness has been certified 4x Platinum by the RIAA, with around 4,248,000 copies sold in the United States alone as of 2011, making it the band's most successful album. It is one of three Disturbed albums to have the Parental Advisory label and contain high amounts of profanity and the explicit content of the song "Down with the Sickness".
Unlike Disturbed's later albums, which are mixed in style, The Sickness consists primarily of heavier songs. In addition, The Sickness includes much more profanity, darker lyrical themes, and more electronic elements than later Disturbed albums.
In 2013, Loudwire featured The Sickness in their "Top 25 Debut Hard Rock Albums" list, placing the album at number 24. 
On March 23, 2010, a reissue of the album was released, which includes B-sides, new artwork, and exclusive online content. This reissue celebrates the tenth anniversary of the release of the album and is available for the first time in vinyl format. Disturbed's guitarist, Dan Donegan, commented on the reissue: "[...] it's the album that put us on the map and launched our career. So we went back into the studio and we remixed it, we're having it remastered, we're gonna put a couple of bonus tracks on there and touch up some of the packaging and the artwork. Just a little collector's item, a little tribute to that album for the fans".
The two songs included in the reissue, "God of the Mind" and "A Welcome Burden", are also included in a B-side compilation called The Lost Children.
2002 international reissue (excluded North America)
"God of the Mind"
"The Game" (live)
"Down with the Sickness" (live)
2010 reissue bonus tracks
"God of the Mind"
"A Welcome Burden"
The track "Stupify" actually lasts 4:07, but skipping to the track or ripping it with an unsecure ripping program produces a song that is 4:33. There is a 0:26 backwards-played instrumental part hidden in the pregap between tracks 3 and 4 that can only be heard by rewinding / playing straight through. It is a sampling of some of the guitar work heard on the next track, "Down with the Sickness".