Adenoviruses (AV), isolated from 138 children during the year 1981 in the Hannover area, were studied by DNA restriction analysis with the enzymes BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, and SmaI and compared with the respective prototypes. Varying fragment patterns were depicted and genome types analyzed. Prototype-like strains of AV1 and 5 were not found. Types 2, 5, 1, 3, and 7 showed decreasing genetic variation in that order. Altered restriction sites were physically mapped on the genome; they appeared to be randomly distributed. The high genetic variability of AV2 and 5 is remarkable for this study population, limited in time and space. Clinical and epidemiological data were also presented in relation to serotypes.