Infant botulism is a rare and life-threatening disease caused by the inhalation of Clostridium botulinum spores and differs from adult forms. We report the case of infant botulism in a 4-month-old boy who was exclusively breastfed without any consumption of honey. He presented with severe and acute encephalo-myelo-radiculitis. The patient was treated without success for suspected “postviral” central nervous system inflammatory disease. The diagnosis was eventually made 20 days after the onset of symptoms on the basis of a stool sample. Recovery was complete. Infant botulism should be suspected when infants present with acute flaccid paralysis or brainstem weakness and specific immunoglobulins should be administered.