Recently, concern has arisen regarding a possible elevated occurrence of ALS among veterans who served in the Persian Gulf during Operations Desert Shield (August 2, 1990 - January 15, 1991), Desert Storm (January 16, 1991 - February 28, 1991) and Clean-up (March 1, 1991 - July 31, 1991). This study involves an epidemiologic investigation into the occurrence of ALS among veterans of the Gulf War. This study will further define the epidemiology of this neurological disease among younger individuals while determining whether there is a higher than expected occurrence. It will also ascertain the etiologic importance of deployment to the Persian Gulf and exposure to specific environmental factors in that geographic area. VA is leading this joint federal government epidemiologic study that also involves DoD, HHS, CDC, and academic centers of excellence in neurology, with advice from the ALS Association.