We studied the efficacy of bromides (BR) as add-on therapy in 11 patients with severe myoclonic epilepsy in infants (SME) and in another 11 with the borderline variant of SME (BVSME). Study subjects were aged 8.5-183 months (mean 64.4 months). Longest duration of BR treatment was 37 months (range 4-37 months; mean 19.7 months). Eight of 22 (36%) of patients with generalized tonic-clonic seizures (GTCS) had an excellent effect (> 75% reduction in total seizure frequency or duration) and 9 (41%) had a moderate effect (50-75% reduction) 3 months after introduction of BR. Twelve months after initiation of BR. 5 of the patients with significant improvement were no longer responsive; ultimately, therefore, 6 had an excellent effect and 2 had a moderate effect. Of those with partial seizures (n = 5) and myoclonic/absence seizures (n = 5), only 1 patient in each group showed a moderate effect at the 12-month time-point. Dosages and serum concentrations of BR ranged from 30 to 100 mg/kg (mean 58 mg/kg) and from 64 to 159 mg/dl (mean 101 mg/dl), respectively. Of the 12 patients experiencing side effects, including drowsiness, appetite loss, and skin rash, 1 required a reduction in BR dosage because of an extensive acneiform rash on the face. The results show that BR treatment holds promise for patients with SME and BVSME and should therefore be investigated further.