Repeated exposure to stress during early life has a lifetime impact on physical and psychological functions. Our study investigated the long-term effects of early life stress (ELS; measured retrospectively) on the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system functions under psychosocial stress among healthy adults. Fifty healthy volunteers (33 male, 17 female, mean age 22.6 +/- 1.8 years) underwent a standardized psychosocial stress protocol (the Trier Social Stress Test), with the collection of salivary cortisol, heart rates, and positive and negative affect. The results showed increases in cortisol, heart rate, and negative affect after the stress inducement. More importantly, a significant negative correlation was found between the severity of ELS and the increase of cortisol to the stress. The severity of stress in one's early life predicted his/her cortisol reactivity to the stress in adulthood. Neither the heart rate reactivity nor the affective reactivity shows significant association with ELS. The blunted cortisol reactivity reflects the alteration of the HPA axis, which may confer the risk for certain stress-related disorders.