Serious adverse effects with antichoreic drugs can occur in patients with acute Sydenham's chorea (SC). The response to conventional treatment in severe SC may also be poor. Thus alternative therapeutic strategies have been developed. We report on four patients with severe acute SC (two with chorea paralytica and two with neuroleptic-induced parkinsonism) treated with i.v. methyl-prednisolone pulse-therapy followed by oral prednisone. The mean+/-SEM clinical rating score dropped from 63.7+/-10.2 to 33.5+/-10.6 in the first month post-treatment but in a lesser degree thereafter. Only one patient developed weight gain and 'moon facies'. This case series suggests that immune suppression with corticosteroids may be an effective and safe treatment in complicated and severe acute SC.