Background: Different studies conducted worldwide among medical students have reported the prevalence of stress ranging from 27% to 73%. Exam stress acts as an acute stressor which affects cognitive functions. It is found that the exam stress elicits elevated activity in the hypothalamic-pituitary-adrenal axis and increased release of cortisol. Aims and Objective: The study was planned to investigate gender difference in perceptions of exam stress and reactions to it among first-year medical students. Choice reaction time (CRT) was used to evaluate the cognitive performance of students during stress-free and stress (exam) conditions. Materials and Methods: The study was conducted on 60 healthy first year MBBS students (30 boys and 30 girls) between the age group of 18 and 20 years. Digital reaction time was used. Randomly occurring visual and auditory CRT tasks were presented to students. First set of readings was taken during stress-free period, and the second and third sets were taken 20 min before first and second terminal practical examination, respectively. Results: The readings were analyzed by unpaired Student’s t-test. Results showed that visual and auditory reaction times were increased in both boys and girls with statistically significant difference between boys and girls in stress (exam) condition, but no difference during stress-free condition. Conclusion: The observation shows that girls tend to perceive more stress than boys which might affect the cognitive functions more, as slower reaction time was observed in girls than boys when they were exposed to stress.