This report describes the first diagnosis of swine influenza H1N2 virus infection in growing pigs in Korea by virus isolation, reverse transcription-polymerase chain reaction (RT-PCR), histopathology, and in situ hybridization. The subtype of swine influenza virus isolates was determined to be H1N2 by RT-PCR. The most consistent and predominant histological feature was bronchointerstitial pneumonia. Lung tissues from these pigs were hybridized with the nonradioactive digoxigenin-labeled complementary DNA (cDNA) probe from H1 HA and N2 NA genes but not from H3 HA and N1 NA genes. A strong hybridization signal was seen in bronchial- and bronchiolar-lining epithelial cells and in alveolar and interstitial macrophages.