Pseudotumour cerebri is a disorder characterized by elevated intracranial pressure in the absence of hydrocephalus and intracranial mass lesions. The cause of this disease remains obscure but has been related to diverse underlying conditions. We report a patient with pseudotumour cerebri, polyarthritis, urticaria, hypocomplementemia and cryoglobulinemia. Serial lumbar punctures were unsuccessful in lowering the cerebrospinal fluid (CSF) pressure. A trial of prednisone, 40 mg daily for 4 weeks, resulted in clinical improvement but was ineffective in lowering the CSF pressure. Circulating immune complexes and complement activation may have played a role in the development of increased intracranial pressure. Cryoglobulinemia should be added to the list of disorders associated with pseudotumour cerebri.