QUINCY, Mass., June 16— Jim Nance, twice the leading rusher in the American Football League while playing for the Boston Patriots, died today. He was 49 years old.

Mr. Nance died at his home, according to a Patriots spokesman, Pat Hanlon. The cause of death wasn't immediately available. Mr. Nance suffered a heart attack and stroke in 1983.

Mr. Nance, one of a long list of big running backs to come out of Syracuse University, where he was also a national champion wrestler, played for the Patriots from 1965 through 1971. He is the team's No. 2 career rusher with 5,323 yards on 1,323 carries.

He rushed for 45 touchdowns and is sixth on the team's career scoring list. He caught 133 passes for 870 yards and one touchdown.

The Boston Patriots, an original member of the A.F.L., became the New England Patriots at the start of the 1971 season, a year after the A.F.L. became part of the National Football League. M.V.P. Award in '66

He set an A.F.L. rushing record of 1,458 yards in 1966 when he was named the league's most valuable player. He also was the league's top rusher in 1967 with 1,216 yards. After having ankle surgery following the 1968 season, he rushed for 750 yards in 1969.

After the 1971 season, Mr. Nance was traded to the Philadelphia Eagles but did not play. After sitting out the 1972 season, he was signed by the New York Jets, rushing for 78 yards in 7 games and catching 4 passes for 26 yards.

He also played two seasons in the now-defunct World Football League.

After he was stricken nine years ago, Mr. Nance overcame paralysis in his left leg and arm. In the past year, Mr. Nance's daughter Nicole died as a result of complications from injuries suffered in a car accident.

Mr. Nance is survived by a daughter, Rachel.

James Nance