Thirteen to 43% of patients with infantile spasms (IS) have other types of seizures, which are considered a feature of an unfavourable prognosis and, to some extent, as a contra-indication for steroid treatment. The present series comprised 43 patients treated with steroids, who suffered from other types of seizures prior to IS. The first seizures resulted from 2 different conditions, correlated to a different outcome of epilepsy. In 27 patients with prenatal encephalopathy, the first seizures were the first manifestation of the epilepsy and IS responded poorly to steroids. In the other 16 patients, the first seizures were occasional, due to acute brain damage, and the following IS responded favourably to steroid therapy. Rational therapeutic indications should take in account the etiology of seizures that precedes IS, and steroids should be administered when IS are due to acute peri- or postnatal acute brain damage.