Epileptic seizures are common in patients with cerebral metastases as well as in patients with primary brain tumors. In cancer patients without primary brain tumors or brain metastasis, epileptic seizures may occur due to metabolic or toxic causes, or due to infections. We performed a retrospective analysis from our neurooncological database concerning the occurrence of seizures in patients with primary brain tumors, patients with cerebral metastases and in cancer patients without brain tumors. Patients with low grade gliomas, such as astrocytoma WHO I + II (69%), oligodendroglioma WHO II (50%), and mixed glioma WHO II-III (56%) were more likely to have seizures than patients with anaplastic glioma WHO III (44%), glioblastoma WHO IV (48%) or meningeoma (45%). In patients with brain metastasis, melanoma (67%), cancer of the lung (29%), and gastrointestinal tumors (21%) were the primaries with the highest frequency of seizures. In cancer patients without brain metastases or primary brain tumors, seizures occurred in 4%. In conclusion, the occurrence of epileptic seizures in patients suffering from primary brain tumors, as well as in patients with cerebral metastases, varied within the tumor entity. Therefore, especially in brain tumors where a higher probability of epileptic seizures is expected, they should be taken into account in the care of cancer patients.