Television evangelist Jimmy Swaggart and his Baton Rouge, La., Evangelistic Association have become involved in a high-stakes legal battle for the estate of a wealthy California woman whom Swaggart met and baptized shortly before she died in 1981.

Thrice-widowed Zoe McDonald Vance changed her will to leave a substantial amount of jewelry, her house and more than $2 million in cash to the dapper, leather-lunged evangelist less than a year after he first visited her at her Southern California home.

Vance, who never had been particularly religious, began watching television evangelism shows sometime after 1978. For nearly a decade before that, from the time her third husband, a professional musician, died in 1969, Vance had led the party life in her million-dollar beach home, traveling and entertaining.

After she became a regular follower of Swaggart, Vance changed her life style and began attending Swaggart's crusades, according to members of his association. During one of his visits to her home, he baptized her in the Pacific.

Not long before her death, she had her lawyer draw up a will leaving to Swaggart's ministry the "rest and residue" of her estate, estimated in excess of $8 million.

Now the will has been challenged by Vance's sister, Mary Katherine McDonald Leone, 69, of Houston and Fort Lauderdale, Fla. Leone, wealthy in her own right, is not seeking to benefit from her sister's estate.

But she has filed actions in Texas and California courts to reinstate a 1976 Vance will that would leave the bulk of the estate to a medical research foundation established in the name of Vance's only son, David Malcolm, who died of kidney disease when he was 16.