Abstract: Objective To perform a questionnaire on the obstructive sleep apnea-hypopnea syndrome (OSAHS) among the prolonged ocean-going shipboard personnel, so as to provide reference data for further study of this kind. Methods During the medical support exercise of " Operation Harmony-2010", a questionnaire on OSAS was performed in the officers and men of the 2 naval vessels involved in the escort mission in the Gulf of Aden. Participating in the questionnaire were officers and men of a certain naval vessels belonging to group A in a prolonged deployment at sea for a duration of 3 months. The other 139 officers and men of the other naval vessels belonging to group B were deployed there for a duration of 6 months. Statistical analyses were made on the changes in the sleep status of the 2 groups both before and after deployment. Then, the sleep time and OSAHS were compared and analyzed between the 2 groups. Results Sleeping time each day for group B was shorter than that for group A. The number of people in group A who had a tendency of developing OSAHS was 19, with the incidence rate being 16. 1% , while 34 people in group B developed OSAHS, with the incidence rate being 24.5%. The incidence rate of group B was obviously higher than that of group A. There were altogether 155 people (61. 3%) in the 2 groups, who thought their sleeping status after deployment became worse, when it was compared with that before deployment. Conclusions Prolonged oceangoing shipboard personnel had a higher incidence rate of OSAHS. With the prolonging of deployment, sleeping among the deployed personnel would become worse and the tendency of developing OSAHS would become higher. This indicated that OSAHS occurring among the prolonged ocean-going shipboard personnel was a medical problem worth further close study.