Objectie: Intensive and quantitative evaluation of the severity and frequency of seizures and ictal signs during topiramate (TPM) treatment. Methods: Twenty patients with refractory partial seizures undergoing presurgical evaluation were randomized into a low dosage (100mg daily) and a parallel medium dosage (200mg daily) group of TPM add-on medication. Study phases included a 3-day baseline video-EEG phase, a 10-day TPM titration phase without video-EEG and a 3-day TPM dose maintenance phase with video-EEG. During the baseline and the dose maintenance phase seizures were recorded using video-EEG monitoring and the following parameters were measured: duration (lasting seconds of each seizure and ictal sign), intensity (on a 0-3 scale), N/24h (numbers of attacks per 24h), D/24h (duration per 24h) of both seizures and defined ictal signs. Results: A total of 399 seizures during the baseline phase and the dose maintenance phase were intensively analyzed. Intergroup comparison suggested that duration, N/24h and D/24h of all seizures decreased more in the medium dosage group computing the reduction from baseline to the dose maintenance phase (P 0.05). There were statistically more significant reductions in the duration, intensity and N/24 h of ictal signs like hypermotoric movements, fumbling and vocalization in the medium dosage group (P 0.05). Conclusion: Topiramate has an early dose-dependant effect on ictal seizures. Short Communication: The present study intensively analyzed the duration, intensity, N/24h and D/24h of ictal seizure manifestations. The quantitative data suggested that topiramate had an early effect on ictal phenomena like ictal hypermotoric movements, fumbling and vocalization (P 0.05); effects were more prominent in the medium dosage group (200mg daily) than the low dosage group (100mg daily).