In the Absence of Truth is the fourth full-length studio album by American post-metal band ISIS, released by Ipecac Recordings on October 31, 2006. The vinyl release was handled by Conspiracy Records.

The album expands upon the group's previous full-length, Panopticon, further exploring lead singer Aaron Turner's clean vocals (though his former techniques, which relied more on screaming and growling, are still present as well). Musically, the album is dynamic, ranging from extended musical ambience to almost tribal drumming. Isis continued their lengthy songwriting; In The Absence of Truth is Isis' longest record, at almost 65 minutes.