All human adenoviruses isolated in Iceland during 1988-1990 have been subjected to restriction endonuclease analysis. Of 55 isolates altogether, subgenus C (Ad1, Ad2, and Ad5) predominated with 42 isolates followed by subgenus B (Ad3 and Ad7) with 12. Analysis of the 9 Ad1 isolates revealed 6 DNA-variants. Among these the established DNA-variants D4, D7, and D10 were recognized. The remaining 3 DNA-variants were primarily found in Iceland. Among the 22 Ad2 isolates, 7 DNA-variants could be distinguished. D2 predominated with 15 isolates whereas the prototype was isolated only once. The novel 5 DNA-variants of Ad2 were all closely related to D2. Analysis of the 11 Ad5 isolates revealed 6 DNA-variants, 2 of which (D2 and D5) were already established. Ice2 and D3 were the most common occurring DNA-variants of Ad5. Ad5 showed the highest degree of genomic variability within subgenus C, both in terms of the low degree of pair-wise comigration of restriction fragments and the number of principal variants of RE-patterns. Analysis of the 9 Ad3 isolates revealed 3 DNA-variants: D3, D10, and Ice1 (a novel DNA-variant that resembles D10). The DNA-variants D3 and D10 were each represented by 4 isolates. The three Ad7 isolates belonged all to the DNA-variant D5.