DANBURY, Conn., March 19— If it was a nervous time for the juniors and seniors at Danbury High School this morning to try their luck with the newly revised and renamed Scholastic Assessment Test, it was doubly so for Jenn Lohmeyer and Kerry Brown.

Ms. Lohmeyer, a junior from Newtown, Conn., and Ms. Brown, a junior from New Fairfield, were standing in the "problem corner" because they had both forgot to bring the required photo ID.

"I had a private tutor and I really want to take this thing," Ms. Lohmeyer said defiantly.

Ms. Brown, who looked as if she might burst into tears, said she had prepared for the new test by watching a video. "My car's in the shop and I left my driver's license in the car," she said.

It was nearly 9 o'clock when the doors closed, and more than 100 students were already in their seats, nervously toying with their pocket calculators, which for the first time were allowed in the test rooms. Hearing the Stories

Edward F. Walsh, the school's retired guidance counselor, who was the test supervisor, was patiently interviewing the students in the problem corner.

"What's the name of the guidance counselor in your school?" he asked Ms. Lohmeyer when her turn came. She told him.

"Here you go," said Mr. Walsh as he scribbled an O.K. on her credentials.

Ms. Brown also passed this preliminary test and both charged off to the real thing.

Jenn and Kerry were among the 210,000 high school juniors and seniors across the country who took the new version of the S.A.T. introduced today.

Most of the 1.2 million students expected to take the test by the end of this year will do so on May 7, late in their junior year, or on a date to be announced in November, in the beginning of their senior year. In the past, slightly more than half the students have taken the test on both occasions, using their better score, although both are recorded.

"We don't know why they pick those dates, but that's the pattern," said Kevin Gonzalez, a spokesman for the Educational Testing Service, which administers the test. Score Counts Heavily

Students approach the S.A.T. with trepidation because their score will be a weighty factor in college admissions and scholarships, and because today's test was the first substantial revision of the test, formerly called the Scholastic Aptitude Test, in 20 years.

After years of criticism that the test was unreliable and biased against women and minorities, the College Board, the nonprofit organization that sponsored the test for 68 years, revised the S.A.T. The new reading comprehension section lays greater stress on analysis, and revised math questions require students to write their answers on a grid rather than pick a multiple-choice answer. The scoring is the same, with a maximum score of 800 on each of the two parts of the test.

The anxiety of students and their parents has given rise to a multimillion-dollar test preparation business. Tens of thousands of how-to-beat-the-test manuals have been sold, and students have packed coaching courses, which cost up to $700 and take up as many as 13 Saturday mornings.

"Enrollments are up dramatically," said Melissa Mack, a spokeswoman for Kaplan Educational Centers, the nation's largest test preparation company.

Students here in Danbury had a variety of views on test preparation. Several said they had taken the $600 Kaplan test and felt reasonably well prepared. Courses Disdained

John Bennett, who lives in Danbury, said he distrusted all preparation books and courses because they offered only "a quick fix."

Another student from Danbury who refused to give his name said his after-school job had made it impossible for him to take a test preparation course.

Jenn was smiling when she emerged three hours later. "Not bad," she said. "No surprises." She said she is applying to Colby College in Maine.

Mr. Bennett looked relieved also. "The new test probed a little more into the reading comprehension," he said, comparing it with the Preliminary S.A.T. "Otherwise, nothing new."

The students will receive their test scores in four to six weeks.