BACKGROUND: It is not clear whether treatment modality (clipping or coiling) affects the risk of seizures after treatment for cerebral aneurysms. OBJECTIVE: To determine whether there is an increased risk of seizures after clipping vs coiling. METHODS: Hospitalizations for clipping or coiling of ruptured and unruptured aneurysms were identified in the Nationwide Inpatient Sample Database for 2002 to 2007 by International Classification of Diseases 9th Revision codes for subarachnoid hemorrhage or unruptured cerebral aneurysm and codes for clipping or coiling. Clipping and coiling were compared for the combined primary endpoint of seizures or epilepsy. The analysis was adjusted for patient-specific and hospital-specific factors using generalized linear models with generalized estimated equations. RESULTS: There were 10 899 hospitalizations for ruptured aneurysms (6593 clipping, 4306 coiling), and 9686 hospitalizations for unruptured aneurysms (4483 clipping, 5203 coiling). For ruptured aneurysm patients, clipping had a similar incidence of seizures or epilepsy compared with coiling (10.7% vs 11.1%, respectively, adjusted odds ratio: 0.596; 95% confidence interval: 0.158-2.248; P = .445 after adjustment for patient-specific and hospital-specific factors). For unruptured aneurysm patients, clipping was associated with a significantly higher risk of seizures or epilepsy (9.2%) compared with coiling (6.2%) (adjusted odds ratio: 1.362; 95% confidence interval: 0.155-1.606; P < .001 after adjustment for patient-specific and hospital-specific factors). Seizures or epilepsy were significantly associated with longer hospitalizations (P < .01) and higher hospital charges (P < .0001), except in coiled unruptured aneurysm patients, in which seizures or epilepsy were not significantly associated with hospital charges (P = .31). CONCLUSION: In unruptured cerebral aneurysm patients, clipping is associated with a higher risk of seizures or epilepsy.