Virginia's health commissioner approved today the nation's first test-tube baby clinic despite strong and emotional opposition for antiabortion groups and others concerned about the moral implications of creating human life in a laboratory.

Commissioner James B. Kenley approved a "certificate of need" authorizing the Eastern Virginia Medical School in Norfolk General Hospital. Doctors there intend to artificially fertilize human eggs in a laboratory, then implant them in women unable to conceive children normally.

"It is a major step in an important frontier," said Dr. Mason Andrews, chief of the school's department of obstetrics and gynecology. He said the clinic, which has already accepted as patients more than 40 couples from around the United States, could begin operation in less than two months.

Andrews predicted that a number of other institutions, including the medical schools of Vanderbilt University in Nashville, Tenn., and Cornell University in New York City, will quickly follow the lead of the small, virtually unknown, six-year-old school that he helped found and finance.

Opponents of the clinic, who flooded Kenley's office here with more than 700 protest letters and petitions with several thousand signatures,, said today they would go to court to stop the project.

"We've asked our lawyers to come up with a way to prevent the hospital from putting up the first two-by-four," said Charles Dean Jr., president of the Norfolk chapter of the Virginia Society for Human Life. Dean said the clinic has been approved without sufficient proof that "in vitro" (artificial) fertilization is a viable technique.

"There was no proper study of the medical, moral, legal and scientific merits . . . meanwhile we're charging off into the darkness, and I feel it's a tragedy and a disgrace."

The project was also condemned as a potential misuse of technology by Ted Howard, coauthor of a book questioning genetic engineering and codirector of the Washington-based Peoples Business Commission.

"This is another step down the road to the age of genetics where human life will be seen as a mere arrangment of chemicals," said Howard. He fears scientists will eventually experiment with human embryos in a quest to produce a perfect human being.

But Jill Schroeder of Norfolk, one of the women who hopes to conceive and give birth successfully at the clinic, hailed Kenley's approval as "the answer to our prayers."

In his letter of approval, Kenley acknowledged the clinic's opponents but said he was making his ruling essentially on the narrow legal ground that the clinic would fill a presently unmet need of enough patients to justify its operation.

"In vitro fertilization will provide another means to rectify infertility problems for those couples for whom existing solutions are not adequate or acceptable . . ." said Kenley. "Much of the comment in opposition to the project did not relate to the statutory criteria by which I am required to make a decision about application," he said.

Kenley said he was satisfied with hospital assurances that the clinic "will be operated pursuant to ethical and legal standards." He and other health department officials refused to make any other public comment today.

"We've never gotten this many letters on any decision before," said one department staff member, referring to a file over a foot thick.

A number of American scientists have applied for federal funds to pursue in vitro projects in this country since the birth 18 months ago of "test-tube baby" Louise Brown in England. But their research has been delayed while Department of Health, Education and Welfare officials wrestled with the issue.

Eastern Medical School, whose faculty includes a number of renowned experts in fertility research, did not require federal funds and therefore took the lead in developing a test-tube program.

The school has estimated that at least 280,000 women in the United States with blocked Fallopian tubes could benefit from the program.

But the project has run into vehement opposition in Norfolk. Opponents came out in force at two public hearings last August and October to denounce the project.

"The last thing Virginia needs is such a laboratory where scientists will be playing God with babies' lives," said one irate antiabortionist.

Opponents say they are particularly concerned that researchers will discard or use for experimentation imperfect embryos before implantation. They are also upset that potential recipients will have the right to abort abnormal fetuses.

But Andrews and other school officials say every successfully fertilized egg wll be implanted in the patient from whom the egg was removed.

Del. Lawrence Pratt (R-Fairfax) said today he will attempt to ensure that the school follows that principle by introducing a bill before the Virginia General Assembly, prohibiting experimentation on human embryos.

Andrews said most researchers agree in vitro fertilization is a proper tool of last resort for women who otherwise cannot conceive a child. He said patients would pay between $3,000 and $4,000 for two implantation attempts and that the clinic's doctors would donate their time to the project.