An 8-year-old, spayed female Labrador Retriever was presented for evaluation of unwillingness to exercise. On clinical examination abdominal pain was elicited, and a midabdominal mass was detected in survey radiographs. Ultrasound-guided fine-needle aspiration of the intra-abdominal mass was done. The cytologic findings indicated chronic granulomatous inflammation with reactive fibroplasia, cholesterol crystals, and extracellular foreign material. The foreign material consisted of opaque, basophilic fragments of uniform width (5–10 μm) and variable length (30–180 μm) and was observed extracellularly and within macrophages. The material was birefringent under polarized light. Histologic examination of the excised mass confirmed the cytologic findings and a diagnosis of gossypiboma (textiloma) was made, consistent with retention of a surgical sponge. This case provides a unique example of the utility of fine-needle aspiration for the diagnosis of gossypiboma.