Skin tumors are rarely observed in pigs, and, in particular, only a few cases of squamous cell carcinoma have been reported. The present case report describes the occurrence of a squamous cell carcinoma located in the skin at the center of the udder of a 14-year-old German Landrace sow. The tumor was spherical and 17.0 cm in diameter. The tissue of the distal pole had a cauliflowerlike appearance, was black and ulcerated with a malodorous exudation. The sow did not show any signs of reduced general condition caused by the tumor. No evidence of metastasis was noted in regional lymph nodes and in the lung. The tumor, which weighed 2.4 kg, was surgically removed. The histopathology revealed infiltratively growing pleomorphic tumor cells and cell aggregations with prominent squamous differentiation. Cells were strongly positive for several cytokeratins by immunhistochemistry. The present findings confirmed the diagnosis of squamous cell carcinoma. After surgery, the sow recovered without complications and remained without recurrence at the follow-up three months later. This is the first report ofa squamous cell carcinoma in the skin in the udder in an old sow.