Abstract
                 Background: The reproductive system of women shows regular cyclic changes that teleologically may be regarded as  periodic preparations for fertilization and pregnancy. These cyclical changes are also associated with cyclical changes in  the level of ovarian steroids. Estrogen is said to have widespread effects throughout the brain regions involved in affective  state as well as cognition. Aims and Objectives: This study was undertaken to observe the effect of gonadal hormones  on auditory and visual reaction time (VRT) across various phases of menstrual cycle. Materials and Methods: The study  was conducted on 30 healthy female volunteers having regular menstrual cycle belonging to the age group of 17-20 years  studying in the first year MBBS at P.E.S. Institute of Medical Sciences and Research using pitch change 1000 Hz reaction  timer. Results: The results of this study reveal that the auditory and VRT was highest during the mid-proliferative phase  compared to premenstrual phase and mid secretary phase. Conclusion: Thus, the fluctuating levels of ovarian hormones  across the normal menstrual cycle influence auditory and VRT and this fact can be taken into consideration during  neurological and behavioral assessment of women.