Fifty-three donors with good semen quality were studied monthly for sperm count and motility over 9 to 22 months. Medical students (n = 31) in freshman and sophomore years subjected to the stress of twice-yearly examinations were compared with nonstudents (n = 22) not exposed to common stressful periods. Sperm count and quality (count X motility) for the student group were significantly elevated during examination months versus nonexamination months. Controls demonstrated no differences over these months. Differences between individuals, donor selection factors, and the effects of variable degrees of stress on sperm transport may have contributed to this finding.