Blood is the third studio album by American progressive rock band OSI, released by InsideOut Music on April 27, 2009, in Europe and May 19, 2009, in North America. Guitarist Jim Matheos and keyboardist and vocalist Kevin Moore started work on the album in 2008, collaborating by email. Matheos would send Moore a song idea which Moore would edit and send back to Matheos. Mike Portnoy of Dream Theater, who performed drums on Office of Strategic Influence and Free, was replaced by then-Porcupine Tree drummer Gavin Harrison on Blood. Matheos played bass guitar on the album, having hired guest musicians to perform bass duties on the first two OSI albums. Mikael Åkerfeldt of Opeth and Tim Bowness of No-Man wrote lyrics and performed vocals on one track each.