The prevalence of constipation in deployed servicemen was determined in a sample of military personnel aboard the USS Iwo Jima LPH 2 during Operation Desert Shield. Results were obtained from a bowel function questionnaire issued to 500 deployed marines and sailors. When constipation is defined as no bowel movement for greater than 3 days, 3.9% of the Marine/sailor personnel are constipated when in their home environment as compared to 6.0% when they are aboard ship and 30.2% while in the field. Alternatively, when constipation is defined as the presence of certain anorectal complaints (hard stools, straining, painful defecation, and bleeding with defecation), the incidence is 7.2% when at home as compared to 10.4% aboard ship and 34.1% in the field. These results confirm that whether constipation is defined as infrequent bowel movements or presence of symptoms of constipation, significantly more servicemen will be constipated when in the field as compared to their home environment. Since approximately one-third of Navy/Marine Corps personnel deployed in a field environment will be constipated, preventive measures ought to be evaluated.