Swine H3N2 influenza virus designated A/Ontario/1252/07 was isolated from a child with parotitis. Diagnosis was confirmed by viral isolation and serological assays. A/Ontario/1252/07 was related to H3N2 triple reassortants that emerged in swine in the United States in 1998. Three of five tested household members were also seropositive for A/Ontario/1252/07.