Recently, several reports have revealed that some simian adenoviruses (AdVs) strains show a close relationship to human AdVs. In the present study, a simian AdV strain named SAdV-ch1 was detected in chimpanzees in China, and its complete genome was determined. Phylogenetic analysis revealed SAdV-ch1 clustering in a clade that was separate from all of the other simian AdVs but genetically close to a human AdV strain, HAdV-18 (GenBank no. GU191019), sharing 92.5 % sequence identity with it. Recombination analysis provided evidence that a recombination event had occurred between SAdV-ch1 and HAdV-61 (JF964962), where SAdV-ch1 exchanged partial of its hexon gene segment with HAdV-61, leading to the recombinant HAdV-31 (AM749299).