In October 1992 after tetanus inoculations of 26 girl students in a village in the Islamic Republic of Iran, an outbreak of psychomotor syndrome occurred in 10. Although only few were affected, the temporary negative impact on public opinion about immunization was serious. Physical and laboratory investigations of the girls were normal. The 10 girls were compared with their 16 classmates. Higher socioeconomic status was protective (P = 0.04) and distance of home from school was relevant (P = 0.03). This is the first report of a health intervention unwarrantedly being held as the cause of an outbreak. The outbreak, however, was managed successfully.