Objective: We evaluated clinical, electrophysiological and radiologic findings of seizures according to sleep-wake cycle properties. Material and Methods: Six hundred and eighty five patients (325 women, 360 men) with a mean age of 29.3 +/- 15.1 (9-81) years that were followed up in the epilepsy outpatient clinic between the years of 2000-2006 were included in the study. Results: The mean age of the seizure onset was 20.5 +/- 16.9 (0-81) years, the mean duration of the disease was 9.22 +/- 9.05 (0-45) years. Seizures were seen in sleep period in 13.4% of the patients (Group 1), in wake period in 41.5% (Group 2) and in diffuse period in 45.1% (Group 3) of the patients. The seizures were classified as partial epilepsy in 83.6% and as primary generalized epilepsy in 16,4% of the patients. Neurologic examination revealed normal findings in 81.5% of the Group 1, in 70.8% of the Group 2 and 58.3% of the Group 3. Type of seizures according to sleep-wake cycle were secondary generalized in 63% of the Group 1, in 43% of the Group 3, and complex partial type in 45.8% of the Group 2 (p<0.001). In respect of electroencephalography the most frequent finding was focal epileptic activity, and the normal finding was the most frequent finding of Group 1 (p=0.015). According to prognosis the seizures were completely taken under control mostly in Group 1 (63%) and lowest success was obtained in Group 3 (35.3%) (p<0.01). Conclusion: The prognosis were bad in patients whose seizures took place in diffuse period.