An objective of this paper was to study treatment outcomes in patients with infantile spasms (IS) in the evolutionary aspects and from the point of view of drug resistance. We have treated 124 children with IS. Standard therapy included hormones synacthen depot (0.03-0.05 mg/kg) or dexasone (0.3-0.5 mg.kg). The drug regimen was as follows: 10 injections daily initially, following with 5 injections every other day, then 5 injections every two days, plus a valproate in dose 30-40 mg/kg/day. Seventy-three patients were followed up: 21 patients continued to manifest spasms despite the use of several adequate and well-tolerated antiepileptic drugs (AEDs) as a monotherapy, as well as a combination therapy. The patients were divided into 2 groups. In Group 1 (n=12) the remission period was from 0 to 4 months, while in Group 2 (n=9) remission lasted from 7 months up to 4 years. The patients demonstrated all types of IS and modified hypsarrhythmia. In Group 1, the patients were relieved of IS in 66% of the cases and the EEGs showed no epileptic activity in 58%. 83% of the patients then experienced a return of IS and 50% of the patients had hypsarrhythmia. Adding 2 and 3 AEDs to the treatment did not bring any change. A transformation of hypsarrhythmia was observed as the patients grew older. All patients in Group 2 had a cessation of IS, and 77% of the patients had no hypsarrhythmia. In one third of the cases, the IS returned while the other two thirds had focal seizures. EEGs predominantly demonstrated the focal epileptic activity. Adding 2 AEDs had positive effect on seizures in 66% of the cases and EEGs improved in 88% of the cases. Adding 3 AEDs had no effect on the course of the condition in one third of the cases, and in most cases the EEGs did not change. In Group 1, the condition was of drug-resistant nature, and in Group 2 we saw a remission in the condition. After the hormone regimen was completed, a relief of the epileptic activity was achieved for most patients in Group 2. In Group 1, the recurrence of IS was in correlation with the persistence of hypsarrhythmia. We have not found any obvious benefit from the use of any one AED or a combination of AEDs. 78% of the patients in Group 1 demonstrated further persistence of IS for several years. In Group 2, the return of seizures and the EEGs were age-dependent and the treatment had a more positive outcome.