Dr. James E. Meredith, director of troubled St. Elizabeths Hospital for the past two years, has been named assistant director for treatment of the National Institute of Mental Health.

Officials of NIMH said they had agreed with Meredith that the time had come for him to leave St. Elizabeths after his successful efforts to win back the hospital's national accreditation led to numerous internal complaints about his leadership of the institution. St. Elizabeths is a federally funded institution run by NIMH.

James Pittman, executive officer of NIMH, said there had been allegations that Meredith had used a government car for personal trips downtown, "but we checked the records back for a year and there was no substantiation."

Asked about the reports, Meredith said, "There was no substance to that. That kind of hurts . . . You're chasing shadows."

According to Pittman, Meredith came to St. Elizabeth's "with a lot of pressure to get the hospital accredited. He came in and surrounded himself with a cadre of people, people he felt comfortable with."

Because Meredith worked closely with a small number of hospital officials, other members of the hospital staff, including some described by Pittman as "line officials," were upset with Meredith's management style.

Pittman said that NIMH officials brought some St. Elizabeth's staff members out to Rockville to discuss various allegations about Meredith's operation of the hospital, but that none of the charges was substantiated.

"He has a record of accomplishment [at St. Elizabeth's] that's going to be hard to replicate," said Pittman of Meredith. "The hospital was able to make some astonishing achievements."

Dr. Herbert Pardes, director of NIMH, said he and Meredith "are pretty much agreed this is a good move."

Asked about staff complaints about Meredith, Pardes said, "if I listened to all the accusations by everybody about everybody else, I'd end up working by myself and placing myself on probation."

As assistant director of NIMH for treatment, Meredith has been given the responsibility of developing a national plan for long-term treatment of the chronically mentally ill, one of the goals of the President's Commission on Mental Health.

Dr. William H. Dobbs, director of training for St. Elizabeths, has been named acting director of the hospital, replacing Meredith. There was no indication when a permanent director will be named.