OBJECTIVE Brain arteriovenous malformations (AVMs) often present with epileptic seizures, but prospective data on the risk of seizures with respect to morphologic AVM characteristics are scarce. METHODS We studied 155 consecutive patients with AVMs from a prospective, single-center database using demographic and morphologic factors based on prospectively coded MRI and digital subtraction angiography (DSA) data. Univariate analysis and multivariate logistic regression models were used to test the effect of demographic (age and sex) and morphologic characteristics (AVM size, anatomic and arterial location, and venous drainage pattern) on seizures as initial presentation in patients with unruptured brain AVMs. RESULTS Overall, 45 patients with AVMs initially presented with seizures (29%). By univariate comparison, male sex (p = 0.02), increasing AVM size (p < 0,006), frontal lobe localization (p < 0.0001), arterial borderzone location (p < 0.0006), superficial venous drainage (p = 0.0002), and presence of venous ectasia (p = 0.003) were statistically associated with seizures. The multivariate analysis confirmed an independent effect of male sex, frontal lobe AVMs, and arterial borderzone location on seizure occurrence. All patients with seizures showed the presence of a superficial venous drainage component. CONCLUSIONS Our study suggests that seizures mainly occur in AVMs with superficial drainage. Other predisposing factors include male sex, increasing AVM size, and frontal lobe and arterial borderzone location. Whether or not interventional treatment has an effect on the long-term risk of epilepsy remains to be determined.