In December 2005 three sheep, originating from Canton Tessin, were presented with cerebrospinal nematodosis. The animals had a history of progressive pelvic limb ataxia and recumbency. The most important clinical findings were an abnormal gait (wide stance, pelvic limb paresis) and decreased sensitivity of the pelvic limbs. The general condition was slightly or moderately disturbed, appetite was normal. Examination of the cerebrospinal fluid revealed mononuclear cells and eosinophils, suggesting a helminthic infection of the central nervous system. Postmortem findings confirmed the clinical diagnosis in one animal as parts of a nematode were found in the thoracic spinal cord. Even though the nematode could not be identified, infection with Elaphostrongylus cervi seems very likely, as the sheep are in close contact with deer on the pastures and the parasite is known to infect goats in Switzerland. This is the first description of cerebrospinal nematodosis in sheep in Switzerland.