A 43-year-old Northeast woman pleaded guilty yesterday in U.S. District Court to mail fraud in a scheme in which she allegedly embezzled $119,003 from money set aside to administer a fund for needy patients at the Washington Hospital Center.

Margarette E. (Tina) Whited, of the 800 block of Taylor Street NE, a hospital employe for 10 years and former secretary and administrative assistant to the chief fund-raising official there, obtained 38 checks by submitting fraudulent invoices to the hospital accounting office, according to court records. Whited either forged her supervisor's signature on the invoices, deceived him into signing them, or signed them herself, court records said.

Assistant U.S. Attorney Thomas J. Tourish Jr. said yesterday that Whited used the embezzled funds for her own benefit, including making mortgage payments on two homes and paying personal bills such as charge accounts.

A hospital spokeswoman said yesterday that the money allegedly stolen by Whited came from the administrative account for the hospital's Needy Sick Fund and not from contributions to that fund. The spokeswoman said that Whited worked at the hospital from December 1971 until she was removed from her job last April.

The case, which was handled by U.S. Postal Service investigators Connie Edwards and Michael Mague, came to the attention of law enforcement officials last March after the hospital received two unsigned letters alleging that Whited possibly was involved in criminal activity.

Whited pleaded guilty yesterday to one count of mail fraud, which carries a penalty of five years in jail, a $1,000 fine or both. She is scheduled to be sentenced on Feb. 24.