The syndrome of parainfectious encephalomyelitis evolves from an antecedent infection. Several etiologic agents have been associated with this complication, although the pathogenesis in each instance may prove to be more uniform. Considerable evidence suggests that the syndrome is mediated immunologically. The seven cases reported here were clinically similar, although the infectious etiologies were diverse. Leptospirosis antedated the neurologic syndrome in two cases, and a "viral" illness preceded the other five cases. The evolution of the syndrome was slowly progressive in each case, and six patients had prominent involvement of rhombencephalic structures. The progressive course was reversed rapidly with eventual full recovery in each instance after initiation of corticosteroid therapy. Our experience with these cases coupled with a review of the literature suggests that corticosteroid therapy should be considered in the subacute or chronic cases of parainfectious encephalomyelitis.