Al Hirt, the portly Dixieland jazz trumpeter who was a symbol of the exuberant laissez-faire way of life of New Orleans, died yesterday at home in New Orleans. He was 76.

Mr. Hirt had been hospitalized until last week at East Jefferson General Hospital in Metairie, La., with liver ailments, Peggy Stegman, his personal assistant, said. He had used a wheelchair for the last year because of edema in his leg, she said.

One of the nation's most recognizable performers in the 1960's, Mr. Hirt recorded 55 albums in his career and won a Grammy award in 1963 for the song ''Java.''

Genial, bearded, sometimes topping 300 pounds and known to some friends as Jumbo, Mr. Hirt was a ubiquitous figure in his hometown. He had roles in several motion pictures, was a minority owner in the city's Saints football team and ran a popular club on Bourbon Street in the city's French Quarter for 22 years; it closed in 1983.

''He's part of New Orleans, like Louis Armstrong,'' said the clarinetist Pete Fountain, a fellow New Orleans resident who knew and played with Mr. Hirt for 55 years. ''When you say Al Hirt, you say New Orleans. When you say New Orleans, you say Al Hirt. We're just lucky enough to be from here.''

Alois Maxwell Hirt was born on Nov. 7, 1922, in New Orleans, the son of a police officer. A child prodigy, he got his first trumpet from a pawnshop at age 6 and played his first gig in 1938 when he was hired to blow the horn at a local racetrack. Besides earning him $40 a week, the job also started a lifelong and often expensive passion for the ponies.

Mr. Hirt attended the Cincinnati Conservatory of Music from 1940 to 1943 and after a three-year stint in the Army started his career as a trumpet player, bandleader and songwriter, touring with big bands, including those led by Tommy Dorsey and Benny Goodman.

He started his own band in 1950 and a combo with Mr. Fountain in 1955. In 1960, he signed with RCA Records, which released his first album the following year. His most popular albums included ''Greatest Horn,'' ''He's the King'' and ''Bourbon Street.'' He also had a pop single hit with ''Cotton Candy.''

He continued to play at local clubs until recently, even though he had to be wheeled onto the stage. It was a tribute to his feisty spirit. Indeed, Mr. Fountain recalled the time in 1970 when Mr. Hirt, riding on a float during Mardi Gras, was reportedly hit in the lip with a brick thrown by a rowdy spectator. ''I think I was bent over, looking up, about to throw some doubloons to some kids when the lights went out,'' Mr. Hirt said. ''I always told him I think he fell on a Courvoisier bottle,'' Mr. Fountain recalled. He said they last played together about two months ago at Mr. Fountain's club in New Orleans.

''He sat in and that was a good time that night,'' Mr. Fountain said. ''He was having trouble getting around because his legs hurt him, because he's so big his knees gave out. But otherwise, he was all right. He played. He tooted with us, all the old favorites that we have done together through the years -- 'Muskrat Ramble,' 'When the Saints Go Marching In,' 'A Closer Walk With Thee,' 'Struttin' with Some Barbecue' and 'Jazz Me Blues.' We played all of those that night.''

Though he was adept at many musical genres, Mr. Hirt was sometimes derided by critics and jazz purists for injecting rock into jazz numbers and pandering to mass tastes.

He often responded by saying he was nothing more than a crowd-pleaser. ''I'm a pop commercial musician,'' he would tell interviewers. ''I'm not a jazz trumpet and never was a jazz trumpet. When I played in big bands for Tommy Dorsey and Jimmy Dorsey and Ray McKinley and Horace Heidt, I played first trumpet. I led the trumpet section. I never played jazz or improvised.''

''Hirt's playing style was never progressive, but more of a swing type,'' Mr. Fountain said. ''But Jumbo could play anything. That's how schooled a musician he was. He was a good musician, very good. He could read all the notes off the page.''

Mr. Hirt is survived by his wife, Beverly Essel Hirt; six children from a previous marriage, Mary Lee Russo of Bethesda, Md., and Rebecca Dickerson, Bridgid Mearns, Stephen Hirt, Rachel Caron and Jennifer Sammons, all of New Orleans; a sister, Rosemary Hirt Rost; a brother, Gerald; 10 grandchildren; six step-grandchildren, and two great-grandchildren.

The trumpeter, who was often also called the ''Round Mound of Sound,'' considered one of his most important performances to have been his 1987 solo rendition of Handel's ''Ave Maria'' for Pope John Paul II during the pontiff's visit to New Orleans.

Alois M Hirt Jr