The incidence of convulsions in patients receiving tricyclic antidepressants or bupropion was reviewed. For both types of drug, the risk of a seizure was dose-dependent and was higher in patients with predisposing factors, e.g., a history of seizures. Patients without a predisposing factor had a convulsion incidence of approximately 0.6%-0.9% (6-9/1,000 patients) when receiving imipramine at doses of greater than 200 mg/day or bupropion at doses greater than 450 mg/day. At lower doses, the frequency of seizures dropped to about 1/1,000 (or less) for imipramine and bupropion. Thus, the risk of a seizure in patients receiving equally therapeutic doses of imipramine and bupropion appears to be comparable.