PURPOSE: Infantile spasms are considered malignant epilepsy of infancy. Primary objectives of treatment are complete control of seizure attack and prevention of further brain damage. The aim of this study is to assess prednisolone(PDL) efficacy in infantile spasms. METHODS: From June 1985 to July 1994, 20 children with infantile spasms who were diagnosed at Kyung Hee University Hospital and were medicated 2mg/kg PDL analyzed retrospectively. RESULTS: 1) The ratio of male to female was 1.9:1. 2) Mean age at onset of infantile spasms is 7.8 month old and mean age at treatment of infantile spasms is 10.3 month old. Mean duration from onset of the disease to the beginning of the treatment is 1.3 months. 3) The most common type of infantile spasms is flexor type which is 10 cases (50.0%) 4) Among the associated conditions, brain atropy is the most common condition (45.0%). 5) Of forteen cases with developemental delay, six cases were controlled and four of the six cases without developmental delay were controlled. 6) EEG findings were improved in sixteen patients (80.0%) 7) The most common combined anticonvulsant is valproic acid. CONCLUSIONS: The effectiveness of PDL in infantile spasm is 42.9% in group with developmental delay. On the other hand, that is 66.7% in group without developmental delay. Also, because PDL have a merit of cheap and easy for oral medication, it will be necessary that PDL can be selected for hormonal anticonvulsant in infantile spasm. But,it must keep in mind that high dose or longterm PDL can elicit serious side effects.