Sid Gillman, 91, a former head coach of the Los Angeles Rams, San Diego Chargers and Houston Oilers professional football teams who was the proponent of an explosive and wide-open style of offense, died Jan. 3 at his home in Los Angeles. The cause of death was not reported.

Mr. Gillman, who had a record of 123-104-7 in 18 seasons as a head coach, was inducted into the Pro Football Hall of Fame in Canton, Ohio, in 1983. His Hall of Fame plaque hails him as an "innovative coach" and "dynamic administrator" who was "a leading authority on passing theories and tactics."

His theories led professional football away from the "three yards and a cloud of dust" strategy to the wide-open passing attacks of today. His short-pass attack to running backs out of the backfield is a feature of the current "West Coast" offensive system.

During the 1960s, Mr. Gillman perfected one of the most devastating aerial attacks of his era. He would regularly send five receivers out, with the running backs supplemented by ends, at least one of whom would go deep. This spread and confused an increasingly tired opposition defense, making it easier not only to throw the ball but to run it.

"Sid is a legend," said Joe Horrigan, vice president for communications of the Pro Football Hall of Fame. "He literally used the pass to set up the run."

Mr. Gillman has been credited with being one of the first coaches to use game films of future opponents to prepare his teams.

He began his career in professional football in 1955 as head coach of the Los Angeles Rams, winning the National Football League's Western Conference title before losing the league championship 38-10 to the Cleveland Browns. He was fired as after compiling a 2-10 record in 1959.

The following year, Mr. Gillman was hired as head coach (he also soon became general manager) of the new Los Angeles Chargers of the upstart American Football League. He coached the Chargers, who moved to San Diego in 1961, to five conference wins and an AFL championship during his first six years with the team.

In the 1963 league title game, against a blitzing Boston Patriot defense, he put his offense in motion, defeating the hapless Pats 51-10. With the Pats blitzing, the Chargers fed the ball to running back Keith Lincoln, who ended the game with 206 yards on the ground.

Mr. Gillman's San Diego teams featured the great quarterback John Hadl, running back Paul Lowe, and Hall of Famers Lance Alworth at wide receiver and Ron Mix at offensive tackle. His coaching staff included future Pittsburgh Steelers' head coach Chuck Noll, future football executive Don Klosterman and future Oakland Raiders managing general partner Al Davis.

In 1969, ulcers forced Mr. Gillman to step aside. After returning in 1971, he quarreled with his bosses and was fired. With the Chargers, he had gone 87-57-6.

In 1974 and 1974, he coached the Oilers, going 8-15. He also worked in the Kansas City Chiefs, Dallas Cowboys and Philadelphia Eagles organizations, usually as an offensive consultant, before retiring from the game.

Mr. Gillman, a Minnesota native, was a graduate of Ohio State University, where he was an All-Big Ten end and played in the first College All Star game in 1934.

After spending a year playing with the Cleveland Rams, he entered the college coaching ranks. He served under the legendary Red Blaik as an assistant coach at Army and was head coach at Denison, Miami and Cincinnati universities in Ohio before becoming the Rams' head coach.

In 1989, he was inducted into the College Football Hall of Fame.

Survivors include his wife; four children; and six grandchildren.

Coach Sid Gillman is shown on the sidelines of a San Diego Chargers game in this undated photo.