Deaths coded to amyotrophic lateral sclerosis (ALS) for the years 1963 to 1967 among U.S. males were matched against military files to identify 504 World War II veterans. Military controls for these 504 men were matched for year of birth, date of entry into military service, and branch of service. Hospital records of 37 representative deaths coded as ALS among veterans were reviewed, and 36 were accepted as definite ALS. Military records were abstracted for information about preservice demographic and other factors, the physical examination for entry into service, and the medical history and factors characterizing the military career during World War II. There was a deficit of blacks with ALS, which did not attain statistical significance (p = 0.08). Several differences in preservice occupations were found: Truck drivers and “operatives” were in excess. There was no significant difference between ALS cases and controls in aggregate scores on sports activity before service, although baseball was more often listed by the ALS cases than by controls. The ALS patients significantly more often gave histories of trauma or surgical operations before service, and during service had a significant excess of hospitalizations for trauma and in particular for fractures of the limbs.