The acting president of the University of Maryland at Baltimore has resigned, effective Monday, saying that after 21 months he was tired of not being given the permanent job.

The resignation of William J. Kinnard is the second trauma in 16 months in the leadership of the professional-school campus and marks the end of a long national search that was unable to come up with a new president.

In an unusual step, University of Maryland Chancellor Donald N. Langenberg has disbanded the search committee and has personally picked a new president to recommend to the Board of Regents.

"It was an extraordinary action. And it was justified in response to an extraordinary situation," Langenberg said yesterday of his decision to nominate the dean of the campus's dental school, Errol L. Reese. "We called off the search because there wasn't a candidate who commanded respect on campus and off -- and who was willing to come."

The administration of the campus, which contains medical, dental, social work and law schools, has been in flux since the resignation of President Edward N. Brandt.

A search committee, formed nearly two years ago, picked as president Augustus A. White III, a Harvard physician who would have been one of the system's top-ranking black administrators. But in August 1989, White quit before starting the job because of a dispute with the regents' chairman at the time.

His decision embarrassed the university and prompted the ouster of then-Chairman Peter F. O'Malley.

Afterward, the regents ordered the search to resume. But, Kinnard said in an interview yesterday, "We were unable to attract outside candidates because of the problems that people thought were present here based on what happened with all the trauma."

Kinnard told the search committee last summer that he was interested in the permanent job. But he said yesterday, "It was clear the appointment was not going to be made in my favor."

"This process dragged on and on and on. I tried to remain committed to the campus, but you can only last so long," said Kinnard, former dean of the school of pharmacy, who now plans to take a sabbatical.

Langenberg said he decided to intervene because the school could not afford to continue with an acting president. He noted that the campus has a half-dozen top vacancies and is facing tough financial decisions.