Influenza A(H3N2) virus was detected in oral fluid from 16/107 children (aged 2 to 12 years) with a clinical diagnosis of mumps, who were sampled between December 2014 and February 2015 in England, during the peak of the 2014/15 influenza season. Sequence analysis of an A(H3N2) virus from a child with suspected mumps showed the virus was similar to other circulating A(H3N2) viruses detected in winter 2014/15, which were antigenically drifted from the A(H3N2) vaccine strain.