This is a report of a case of Ki-1-positive large-cell anaplastic lymphoma in an 87-year-old man diagnosed on pleural and peritoneal fluids by cytomophologic and immunohistochemical examination. Papanicolaou-stained smears revealed many single, large neoplastic cells containing one or two nuclei with occasional multinucleated cells having a wreath-like nuclear arrangement. The tumor cells expressed Ki-1 antigen and epithelial membrane antigen. This is the first known report of Ki-1 lymphoma diagnosed initially on cytologic examination of pleural and peritoneal fluids.