Primary bladder signet-ring cell carcinoma (SRCC) is extremely rare and associated with an aggressive course. To our knowledge, we describe the first metastatic bladder SRCC identified in cerebrospinal fluid (CSF). A 68-year-old male with 1 year history of primary bladder SRCC with spinal metastasis presented with multiple falls and loss of consciousness. Brain imaging showed high signal in the frontoparietal sulci and superior cerebellum. CSF analysis was significant for increased leukocytes with monocyte predominance while protein and glucose values were within normal range. There was a hypercellular population of pleomorphic tumor cells with signet-ring morphology, similar to those seen in his diagnostic bladder biopsies. The signet-ring cells were positive for cytokeratin 7 and 20 and negative for CDX-2 and prostate-specific antigen. The patient's clinical condition rapidly deteriorated and he died less than a week after presentation. At autopsy, brain sections revealed signet ring cells in the meninges overlying the cerebrum, cerebellum, brainstem, spinal cord, and pituitary with superficial invasion of the brain parenchyma. No brain parenchymal lesions were present. This case illustrates a unique complication of primary bladder SRCC. Diagn. Cytopathol. 2017;45:73–76. © 2016 Wiley Periodicals, Inc.