The evolution of 1217 epileptic patients submitted to anti-epileptic drug treatment is studied. Barbiturates, hydantoin, primidone and/or trimethadione were administered. The study was made in regard to the age of onset, the disease duration and the frequency os seizures. Concerning the age of onset the author draws the following conclusions: the evolution was worse in the cases with onset in the first decade; considering only these cases, a worse evolution was not found in the patients whose disease had begun in the first year; when the disease started at 10 years or more, the age did not influence the evolution. The greatest the disease duration the lowest the remission index; the cases with less than one year of disease presented the best evolution. The evolution was worse in the most severe cases: 30,5% of remission in the cases with more frequent fits against 47,6% in the cases with less than one seizure each 90 days. Since some initial forms, even when submitted to early treatment, had bad evolution, the presence of imponderable and unpredictable factors exercting negative influences in the prognosis of the epilepsies is admissible.