Abstract
Rabbit antisera were prepared against 16 strains of adenovirus type 3 and 8 strains of type 7. Type 3 strains were indistinguishable by hemagglutination inhibition and neutralization tests. Strains of type 7 likewise were antigenically similar. There is essentially no serological crossing between types 3 and 7. The Takeuchi strain which apparently is a 3-7 hybrid was neutralized by both type 3 and 7 antisera and its antisera likewise neutralized all type 3 and 7 strains. Antisera prepared to types 11 and 14 contained neutralizing antibody to all strains of type 7 but not type 3.