It is often argued that a blend of personality characteristics is known to affect the immune system. It has been identified that The Limbic Hypothalamic Pituitary Adrenal (LHPA) axis acts as the principal path of the communication between the immune system and the central nervous system. so this study was done to find out the relationship between Big Five personality traits and Total Peripheral Lymphocyte Count (TPLC) as a parameter of immunity in an undergraduate medical students (n=150). We calculated the correlation between personality variables and Total Peripheral Lymphocyte Count (TPLC). Further regression analyses were performed using personality variables as predictors and Total Peripheral Lymphocyte Count (TPLC) as criteria by using various statistical measures.