Three sisters presented within a one-week period with central nervous system manifestations of mumps. One had the more commonly observed aseptic meningitis syndrome while the other two had spinal paralytic disease. The latter manifestation is an unusual and rare complication of mumps. The major features of their illness included transient, asymmetric flaccid paralysis of the lower extremities accompanied by hyporeflexia, severe myalgia, and intact sensory modalities. Transient urinary sphincter dysfunction and extensor plantar responses were evident in one of the two sisters.