It doesn't rival the escape of the Briley brothers and four other death-row inmates last spring in nearby Virigina, but the escape of three prisoners from the federal correctional institution here Sunday night -- following the escape of another inmate Friday night -- has set off the biggest womanhunt in memory.

U.S. marshals, state police and local sheriff's officers were combing the area surrounding this tiny town in the bucolic Greenbrier Valley, the home of the nation's only federal penal institution for women. Until Sunday night, a mass escape was considered to be two women. It is not unusual, authorities said, for two women to run away together, though they almost always are picked up nearby a short time afterward.

The recent escapees were a Virginia Beach, Va., woman who stole $100,000 from the bank where she worked; two Oklahoma women who took money from banks and a South American woman who was part of a major drug ring.

The three women who escaped Sunday night apparently scaled the eight-foot fence that surrounds the 96-acre, campus-like prison, authorities said. None was believed to be armed, or particularly dangerous, so the search that ensued did not include issuing weapons to any of the staff members who combed the narrow roads and river banks that are the only way out.

The only clues to their escape were several sets of footprints found in the snow outside the fence. The tracks appeared to be headed north, to the logical escape route, I-64, a dozen miles to the north.

Testimony to the ruggedness and isolation of the area surfaced in another recent escape.

Annie Jackson, 39, ran on Nov. 21, but got no farther than the center of town, where her dehydrated body was found Dec. 30 in an abandoned warehouse. Others have tried to take a boat across the Greenbrier River, only to be turned back by its swift current, which today was swirling with whitecaps.

So while escape looks easy -- the front gate is open, guarded by an unarmed officer sitting in the warmth of the Sarah Bernhart reception center -- success is limited.

Last year, 18 women ran, including three who did it twice, but nine were quickly returned, including Jackson. The other nine are still at large. In 1983, escapes totaled seven, six of whom are back on the grounds.

David Helman, executive assistant to Warden Gwynne Sizer, said three is the largest number of women to try to escape in his 12 years here.

Helman believes there is no connection between the escape Sunday night and Friday night's flight of Maria Cardenas-Velillia. Cardenas, 50, from Caldas, Colombia, was serving a 4 1/2-year sentence for her part in a $1 million-plus cocaine sale in Miami.

The three who fled together, all white women, were:

* Evelyn Hewings, 33, of Virginia Beach, who left her job as a teller at a drive-in branch of the Virginia National Bank in Norfolk in 1980 with about $100,000 in cash. She was arrested in Seattle. Prison records here do not show whether the money was recovered.

* Patricia Roberts, 51, of Eufala, Okla., a parole violator originally sentenced to serve five years for embezzling $84,000 from an Oklahoma bank.

* Marjorie Potter, 49, of Warner, Okla., who took $4,000 from a drive-in bank window in Muskogee, Okla., after saying "I have a bomb" to a teller.

Potter and Roberts lived in the same cottage.

All three women disappeared sometime between dinner and a 9 p.m. room count Sunday.