We report a series of four patients in whom the onset of systemic cancer was heralded by dysautonomic symptoms and a neurological non-metastatic complication mediated by immunological and endocrine factors. The series includes: a patient with acute leukaemia and autonomic sensory-motor polyradiculoneuropathy, a patient affected by colon carcinoma and autonomic neuropathy and limbic encephalitis, a patient with lung cancer and autonomic neuropathy and hypercalcaemic encephalopathy, a patient with small cell lung cancer associated with autonomic neuropathy in Lambert-Eaton Myasthenic Syndrome (LEMS) and syndrome of inappropriate ADH secretion (SIADH). We underline the prognostic importance and discuss the possible etiopathogenetic role of autonomic dysfunction, which is frequently associated with paraneoplastic neurologic syndromes of autoimmune and/or dysendocrine origin.