The effects of acceleration (Gz) on changes in the levels of cortisol in saliva and of cortisol and testosterone in serum have been studied in 48 cadet pilots exposed to a linear acceleration gradient (0.2 G/s) until a loss of coordination when the mean G value was found to be 5.94 +/- 0.57. Three patterns of salivary cortisol responses were discerned based on Gz-induced significant changes: increase (I; n = 20), decrease (D; n = 8), the magnitude of changes being dependent on the pre-Gz values. Fifteen min after the Gz load, the mean salivary cortisol was significantly higher from the pre-Gz value in all subjects combined. In 19 subjects, who consented to blood sampling, significant increases in serum cortisol were observed both 3 and 15 min post-Gz (by 37 and 57% respectively) while, a significant increase in serum testosterone concentration has been observed only 3 min post-Gz. Testosterone levels 3 min post-Gz were significantly correlated with the final Gz values (r = 0.54; p < 0.05). A significant correlation was also observed between all salivary and serum cortisol values combined (r = 0.696; p < 0.001). It has been concluded that acceleration stress, although of very short duration, proved very potent in eliciting glucocorticoid and androgen responses.