Undergraduate sex, made famous by Harvard, is plaguing campuses as diverse as Oxford University and Lawrence College in Appleton, Wis.

At Oxford, Roger Lee Hostin, a 21-year-old American student, was suspended last week for keeping a girl in his room at night. Hostin said he invited the girl to spend the night because it was impossible to find a taxicab in the heavy British fog. When the girl's friends telephoned Hostin's dormitory, university officials found her in the American's closet.

The incident aggravated an already heated controversy between the university administration and the Oxford University Student Council, which said in a report earlier this fall that students' sexual behavior is not a matter for college discipline.

At Lawrence College, where Nathan M. Pusey served as president before coming to Harvard, the board of trustees voted unanimously last month to squelch a student proposal for "invitational open houses" in dormitories.

Explaining the board's action to the editor of the undergraduate newspaper, President Curtis W. Tarr said:

"The further we go in the direction of more of this kind of freedom in the dormitories, the more likely we are to attract the kind of student that we'd rather not have. If we were to superimpose upon the Lawrence campus--given our facilities--the present rules of a school like Harvard, we would attract here at this midwestern setting the kind of student who attends Harvard."

Tarr is an alumnus of the Business School.