More than 50 Anacostia youngsters suffered apparent food poisoning Tuesday evening after most of them ate spolied turkey served at lunch in the Congress Heights Elementary School cafeteria earlier that day.

Three of the children, aged 7, 9 and 10 were admitted to Greater Southeast Community Hospital suffering from vomiting, diarrhea and dehydration, a hospital spokeswoman said. They are expected to be released today.

Forty-nine other students ranging in age from 3 to 9 were released after treatment at Greater Southeast and Hadley hospitals for less severe vomiting and upset stomachs. Three to four teachers also were stricken.

City health officials said they believe the outbreak was caused when leftover turkey that had been cooked on Monday was cut up, improperly refrigerated, then made into turkey salad sandwiches for lunch on Tuesday.

"The turkey stayed warm for so long that bacteria grew and gave off" the poisons that made the children and teachers sick, said Herbert T. Wood, chief of the city's bureau of occupational and institutional hygiene.

The turkey was placed in the school's walk-in refrigerator Monday afternoon along with nine trays of hot jello, said Dr. Martin Levy, the city's chief of communicable disease control.

Levy said the center of the turkey probably did not cool quickly enough to prevent the unidentified bacteria from growing.

Both officials said samples of the turkey salad had been taken to the city's laboratory for examination and identification of the bacteria. They said test results probably will not be in until Monday.

Wood said the bacteria probably was trasmitted to the turkey when someone touched it with a dirty knife fork, spoon or unclean hands.

Two of the students who became ill did not eat lunch at the school Tuesday, but they suffered the same symptoms as the others, according to a Greater Southeast spokesman. Officials suggested that they may have developed upset stomachs for other reasons or their cases may have been psychosomatic.

Congress Heights Elementary, located at Sixth Street and Alabama SE, has an enrollment of about 550 and a Project Head Start program for preschool children.