This Gulf city, which for most of last year desperately sought, and finally found, a specialist to care for new-born babies, is without one again.

Attention focused on Beaumont, which has an infant mortality rate nearly double the national rate, when it sought early release from the Navy for a specialist who had promised to set up practice there.

That effort failed. Then, last fall, Dr. Remasamy Sephupathy, an Indian'born neonatologist, was recruited from Illinois. He took charge fo the neonatal clinic at St. Elizabeth's Hospital.

But last Saturday, a few hours after jogging several miles, Sephupathy, 34, was felled by a fatal heart attack.

"We have suffered a tremendous setback," said Dorothy Yentzen, assisstant administrator at St. Elizabeth's .

Nine infants now in the neonatal clinic are being cared for by Sephupathy. Efforts to replace him will begin immediately, but Yentzen said there is no telling how long it may take.

The absence of such a specialist is critical in Beaumont. The city has a population of 127,000, and its three hospitals serve as a medical center for another 450,000 in outlying areas along the Louisiana border. Some 8,000 babies are born here each year, and 19 die out of each 1,000; nationally it is 11.6. Worse, the rate has been rising in East Texas when it is declining almost everywhere else in the state.

Area doctors have cited tha lack of a neonatal specialist as a principal factor in the high death rate.

Until Sephupathy's arrival, seriously ill infants were taken to hospitals in Houston or Galveston.

Early last year, Dr. William Fawcett, a native of the Beaumont area, volunteered to take over St. Elizabeth's neonatal clinic if the Navy, which paid for his final year of medical school, would replace him from a resulting obligation to complete five years of service.