SEPSISM was formed in Pacoima, California, in September of 1990 by drummer Phillip Hernandez, vocalist Fernando Avila, and guitarist Jeff Sheldon. Soon after, the band began playing shows throughout Southern California. In 1992 after several line up changes, SEPSISM recorded their first demo, consisting of five songs, giving the local scene a long awaited release, and getting SEPSISM featured in fanzines and on compilations.
In May of 1993 after enlisting guitarist Leon Morrison, SEPSISM returned to the studio to record their second demo, which contained six new songs, again SEPSISM was featured in fanzines and on compilations, and the band's following began to grow, soon after, SEPSISM parted ways with long time guitarist Jeff Sheldon.
In August of 1994 after recruiting lead guitarist Danny Halstead SEPSISM again entered the studio to record their "Severe Carnal Butchery" demo, which contained five songs. This was SEPSISM's best recorded, produced, promoted, and distributed demo to date, soon the release of "Severe Carnal Butchery" helped SEPSISM become well known in the underground all over the world, and led to SEPSISM opening shows for many of DEATH METAL's elite. Later that year SEPSISM parted ways with Danny Halstead.
In November of 1995 SEPSISM returned to the studio to record five new songs for a split CD with another Southern California band, when this did not work out as planned, the songs were shopped around to various independent labels, and SEPSISM signed a deal to release the songs through Bovine Records. This CD was to be entitled "Necrotic Flesh Rot", but due to unfulfilled promises regarding the release date, SEPSISM was forced to demand the return of their materials from Bovine Records. "Necrotic Flesh Rot" was never released.
In April of 1998 after the departure of long time bassist Marcos Menendez, SEPSISM entered the studio to record their first full length CD entitled "Purulent Decomposition", which contained the four unreleased songs from "Necrotic Flesh Rot", two songs from their first demo, three songs from their second demo, and three new songs. Shortly after, SEPSISM signed a three-album deal with REPULSE RECORDS, and in late May of 1998 SEPSISM recruited session Bassist Mondo Madrigal to help out with shows. Several months later SEPSISM recruited bassist Danny Bourlier who soon after parted ways with SEPSISM.
In February of 1999 "Purulent Decomposition" was released and SEPSISM played many shows despite the continuing lineup changes.
In January 2000 SEPSISM recruited lead guitarist Salvador Altamirano and prepared to go on their first EUROPEAN TOUR. The ""Purulent Decomposition" TOUR 2000" began March 9 and ended April 2nd passing though Czech Republic, Germany, Holland, Belgium, France, Spain, Portugal, Slovakia and Poland. In April 2000, after returning home from Europe, SEPSISM parted ways with lead guitarist Salvador Altamirano, and began working on material for a new album.
In June of 2001 SEPSISM recruited new bassist Raffi Roumdikian.
In 2002 SEPSISM signed with From Beyond productions to release the new album 'To prevail in disgust', which will be out in April 2003.