Two women pleaded guilty in Prince George's County Circuit Court yesterday to criminal charges stemming from a computer fraud scheme that bilked nearly $500,000 from a District of Columbia Pension health and welfare fund over a eight-year period.

The scheme involved an employee of a trust fund corporation who diverted union pension funds to a relative by filling out fraudulent computer data.

The 36-year-old former employee of Carday Associates, Jennie J. Barger, pleaded guilty to false pretense along with her 37-year-old sister-in-law, Ervie A. Edgerly, according to a Prince George's County state attorney spokesman.

The two women, who could receive prison sentences of up to 10 years, participated in the scheme that involved the mailing of 608 checks worth $492,138 between January, 1967, and July, 1975, the state's attorney spokesman said.

It was only after a routine audit last year, according to Assistant State's Attorney Robert C. Bonsib, that "huge" amounts of money were discovered missing from the account of Local 77 Engineers Operators Union Health and Welfare Fund. The fund is controlled by Carday Associates, of 1003 K. St. NW.

That firm, headed by former Maryland Rep. Carlton R. Sickles, is currently involved in a civil suit to get back $536,000, which includes the stolen money plus interest.

According to Bonsib, Barger filled out medical insurance claim forms, processed them through a computer, and sent checks ranging from "$1,300 to $1,400 on some occasions" to her sister-in-law in Hyattsville who then cashed them.

Mrs. Edgerly, a Prince George's County school bus driver, and her husband, a motor vehicle operator at Walter Reed Hospital, simultaneously owned homes in Accokeek and Hyattsville, property in Louisa County, Va., three cars, two motorcycles and eight show dogs.

The Bargers, meanwhile, added a $5,000 addition to their home and purchased numerous Cadillacs, boats, a motorcycle and a gun collection, according to investigators.

Originally, Mrs. Barger, formerly of Upper Marlboro and now living in Leesburg, Fla., and Mrs. Edgerly, of 4018 Kennedy St., Hyattsville, were indicted along with their husbands on Dec. 1 1976. The Prince George's County State's Attorney's Office later dropped the charges against their husbands.

Currently Mrs. Edgerly is free on bond, but Mrs. Barger asked yesterday that her bond he revoked, according to a state's attorney office spokesman. He said Mrs. Barger wanted to begin serving her time.

Prince George's County Circuit Court Judge Samuel W. H. Melony, who presided over the hearing, set June 22 as the date for sentencing.