Five months ago, Sabrina Holston, 18, a recent Anacostia High School graduate, had just lost her job as a drugstore cashier and was unsure of where to find another.

Next week, she will become a teller at the United National Bank as a result of a new training program sponsored by the city's antipoverty agency to prepare small groups of low-income unemployed persons for jobs in banks and credit unions.

"It's great and I worked for it," an excited Holston said recently. "My mother is overwhelmed."

Holston is among the first 12 participants in the $29,000 federally funded program that began in March. The 12-week training program is a cooperative venture between the United Planning Organization and several of the city's banks and savings and loan institutions that provided UPO with technical assistance and sites for the training.

The students, after six weeks of classroom instruction in a variety of subjects, from settling accounts, handling customer relations to training with paper money at the downtown UPO headquarters, are now working as interns at participating institutions. They include Washington Federal Savings and Loan Association, Independence Federal Savings and Loan Association of Washington, the American Federation of Community Credit Unions, D.C. National Bank, the credit unions of the U.S. Department of Housing and Urban Development and the Coast Guard.

UPO executive director Ernest Ward said the agency is training young unemployed persons to become bank tellers because there are job openings in that field. "I have actually seen other kinds of training programs where young people . . . were trained to become case social service aides or youth workers," he said.

"We know in this era of dwindling resources for social welfare . . . there are a lot of folks with master's degrees in social work who are out of jobs. The kinds of training program that we are trying to develop now are really based on documented demand."

The students, who must be high school graduates or have a general equivalency diploma, range in age from 18 to 30 and are mostly women who formerly worked as teachers aides, cashiers and receptionists. They are paid a $30-a-week stipend by UPO, including the time they actually work in banks, to cover their expenses in participating in the program. They had generally earned less than $11,000 a year. All were referred to the training program by the D.C. Department of Employment Services.

Two of the students dropped out--one to take another job and a second for lack of interest--Doris Stashenko, a UPO official, said. Of the remaining 10, only Holston has gained a permanent job so far. UPO officials said they will try to help the trainees who are not hired by the banks where they are working to find permanent jobs.

A second group of 13 trainees will begin classes in June, but it is unclear how long the new program will last because the federal money runs out Sept. 30.