A new military medical school - the expensive dream of a once-powerful Louisiana congressman - has been all but pronounced dead at the unripe age of 100 days.

Rep. Melvin Price (D-II), chairman of the House Armed Services Committee, predicted that the House will back President Carter's action, disclosed Tuesday in the Carter budget, to kill the school.

What is formally known as the Uniformed Services University of the Health Sciences - so far, two unfinished buildings near Bethesda Naval Hospital and 32 students in makeshift classrooms at Walter Reed Army Hospital - is the product of the long crusade of former Democratic Rep. F. Edward Herbert, chairman of the Armed Services Committee, to create a university to train military doctors. The school opened Nov. 15.

"I think" the Carter action "was a mistake," Price said. "The school is needed to train an adequate military medical corps."

But "I have no intention" of trying to restore the money "because at the moment it would be futile." he said. "If there were a House vote, it would probably be a vote to go along with the retrenchment, I'm still talking to people to see if there's any hope, but so far I haven't got that encouragement."

The news of the Carter action was called a blow to the students and to future military medicine by school officials. But "we don't think there will be any problem" placing the students in other schoools at government expense if Congress backs the President, said Army Lt. Col. Ronald Blacnck, assistant dean for student affairs.

One building, 75 per cent complete, will probably be finished and "there is a real possibility" of efficiently using it for medical research or training, Defense Secretary Horold Brown said. The future of the second building, 15 to 20 per cent complete, is less certain.

What is certain, by administration thinking, is that the government can save millions by not running another new medical school when new or expanded civilian schools are already training so many doctors that many authorities think there will be a doctor surplus by the 1980s.

Brown said $41.9 million has been spent on the military school already and it would cost "at lerast $100 million total" and perhaps $200 million to complete, plus $14 million in fiscal 1978 to operate, a figure that would grow as future classes grow.

A school spokesman said the cost of building the two buildings would be "only $66.6 million, not $100 million."

But the school's foes - including the General Accounting Office and Defense Manpower Commission - have long maintained that it would cost between $150,000 and $200,000 to train each graduate compated with around $34,000 to provide scholarships in civilian schools.

In reply, the school's friends said a special was needed to train the special doctors the military needs, and more importantly, that these doctors would serve longer than converted civilians. Thus, they said, the real cost to the taxpayer would be less per yerar thhan the cost of constantly subsidizing and recruiting civilians.

Hebert, who was defeated in a primary last year, long argued this and was largely unheeded, even by Defense Department medical officials in the early Nixon years. But he finally won the support of then Defense Secretary Melvin Laird, Senate Armed Services Chairman John Stennis (D-Miss.) and Congress.

At the school's ground breaking 19 months ago, David Packard - former deputy defense secretary and the school's acting president - call Hebert the school's "father."

Packard called the possible closing a "disaster" yesterday and promised his effort to persuade Congress to reverse Brown's definitive-sounding words: "The University of the Health Sciences is to be closed."