On his first day in Mathematics 55, Stephen S. Wang '98 didn't notice anything unusual.

Then, before the class started, a student leaving the room from the previous course asked, "Hey, is this an all-guy class?"

Wang looked around. The top-level multivariable calculus course has 15 undergraduates, and all of them were, indeed, male.

The lack of women doesn't affect the class atmosphere, he says.

"It's just a math class, as far as I'm concerned," Wang says. "It might matter in a lit class, where you need different perspectives, but not in math."

None of the 21 women who tried were tested into the class; 68 men took the test, according to department administrator Ruby Aguirre.

And women are not just under-represented in upper-level courses; Math 25, the class most students take if they fail to get into Math 55, has only "at least 10 women" in a group of 50, says Math 25 TF Larry E. Wilson '97.

The all-male class, and its heavily male lower-level counterpart, are examples of what many see as a problem in several math and applied and physical science departments at Harvard.

"In the entire pool of undergraduate [math] concentrators, men far outweigh women," says Senior Preceptor in Mathematics Robin Gottlieb. "The math department is always concerned about the number of women undergraduate concentrators."

A 1991 report by the Faculty's Standing Committee on the Status of Women said that Harvard had a widespread problem recruiting and retaining women in science, particularly at the graduate and faculty level. A 1993 update reasserted most of the report's main points.

"The sciences present special problems for women at all levels," the report said. "Women students often find themselves actively dissuaded from doing work in certain areas of science."

In math, Gottlieb says she last week noticed a sign-up list posted in the department for the prestigious national Putnam Mathematical Competition. On a long list, there was only one female name, she says.

This year there are about 140 math concentrators, according to department undergraduate studies coordinator Svetlana Alpert. Less than 30 percent of those 140 are women, she says.

And while several professors say they seem to see more women in their classes, Alpert says the proportion of undergraduate women in the department has changed little in the past few years.

The math department faculty is also largely male: only five of the 36 teachers in the department are women. None of the department's 16 tenured professors are women.

Why the Dearth?