This study assessed the sources of perceived stress for aircrews taking centrifuge training and factors perceptibly increase or alleviate the perceived stress of trainee when undergoing centri-fuge training. A questionnaire (see Appendix A) was distributed to military aircrew in Taiwan who were scheduled to undergo human-use centrifuge between January 2009 and December 2009. Military aircrews were approached immediately after undergoing human-use centrifuge training and asked to complete the self-administered questionnaire. It contained 30 items identified from military instructors and aviation physiology experts. Each used a five-point Likert scale (1 ¼ strongly disagree; 2 ¼ disagree; 3 ¼ neutral; 4 ¼ agree; 5 ¼ strongly agree). Respondents were asked to rank the stress-influence items. The questionnaire was piloted on a small sample (48) of subjects to assess its content validity, internal consistency and reliability. It was then directly distributed to the 611 military aircrew members scheduled to take centrifuge training in 2009. Out of these, 460 respondents returned completed usable questionnaires, which, with the 48 pilot responses, provided a total of 508 usable responses. Table 1 summarizes the sample characteristics. Among the 508 respon-dents, all military ranks were well represented (39 medical tech-nicians; 73 student-officers; 105 Second Lieutenants; 82 First Lieutenants; 48 Captains; 51 Majors; 88 Lieutenant Colonels, and 22 Colonels). Forty percent of the respondents had more than 500 flight hours and approximately one-third (32%) had more than 1,000 flight hours. About 34 percent of the respondents were pilots of Taiwanese second-generation jet fighters, (including F-16A/B, Mirage 2000-5 and IDF). Finally, more than 27 percent of the respondents had served in the air force for more than ten years.