We evaluated the association between the stress levels and biological responses of nursing students in a clinical practicum. The subjects consisted of 28 third-year nursing students at the nursing department of College A. The degree of stress was evaluated using the Japanese version of the State Trait Anxiety Inventory (STAI). As parameters of biological responses, serum estrogen, salivary cortisol, and salivary IgA were measured. These measurements were performed twice (before and during the clinical practicum). Before and during the practicum, the STAI state anxiety score increased from 46.3 ± 8.1 to 52.3 ± 8.9 indicating the nursing students' practicum-associated stress. No changes were observed in the salivary cortisol or IgA level, but the serum estrogen level decreased during the practicum from 36.7 ± 14.7 to 27.0 ± 9.2 suggesting the inhibition of estrogen secretion.