Technical Abstract: Seven members of a 15 man military team which had operated in rural Malaysia developed an acute illness consisting of fever, myalgias, bronchospasm fleeting pruritic rashes, transient lymphadenopathy and subcutaneious nodules associated with eosinophilia, elevated erythrocyte sedimentation rate and elevated levels of muscle creatinine kinase. Sarcocysts of an unidentified Sarcocystis species were found in skeletal muscle biopsies of the index case. Albendazole ameliorated symptoms in the index case; however, his symptoms persisted for over five years. Symptoms in five others were mild to moderate and self-limited, and one team member with laboratory abnormalities was asymptomatic. Of eight team members tested for anti-Sarcocystis antibody, six were positive; of four with the eosinophilic myositis syndrome who were tested, all were positive. We attribute this outbreak of eosinophilia-myositis to accidental tissue parasitism by Sarcocystis.