Medical students are considered to have performed favorably if they graduate without repeating a year and pass the National Examination for Medical Practitioners on the first attempt. The 715 students who entered Osaka Medical College from 1991 through 1997 were divided into groups on the basis of sex and the interval between high school graduation and medical college entrance. The percentages of students having performed favorably were compared between the groups. The rate of favorable performance in medical courses (and of passing the National Examination on the first attempt) was higher for students who entered college immediately after high school graduation than for students who entered college more than 1 year after graduating from high school. However, when students were divided by sex, male students showed this difference, but not female students did not. Next, we divided the 715 students into two groups on the basis of whether they chose biology as a subject for the college entrance examination. We found no difference in the rate of favorable performance between students who chose and did not choose biology. Therefore, we conclude that students can perform well in medical college, even if they do not choose biology as an entrance examination subject. However, among female students who entered college directly after high school graduation, the rate of favorable performance was higher for those who chose biology than for those who did not choose biology.