Although aseptic meningitis, lethargy and irritability occur frequently in Kawasaki disease and infantile polyarteritis nodosa, other neurological manifestations are rare. The authors report one case of Kawasaki disease and one of infantile polyarteritis nodosa, both associated with acute hemiplegia. Both patients had received courses of oral corticosteroids for their underlying disease prior to the onset of the hemiplegia. Pathological studies, as well as the four previously reported cases, are reviewed.