Background: This retrospective study assessed the efficacy and tolerability of sulthiame as a treatment in children with epilepsy. In Canada, sulthiame is only available through Health Canada’s Special Access Program. Methods: Patients who received sulthiame at the Montreal Children’s Hospital from April 2012 to March 2023 were included. Patients’ medical charts were reviewed, and clinical data was extracted from neurology clinic notes and electroencephalogram (EEG) reports. Efficacy was assessed by comparing seizure frequency and frequency of EEG epileptiform abnormalities before and after initiating sulthiame, while also noting any reported changes in cognition or behaviour. Results: Sixteen patients were included (10 males, 6 females), all of whom had drug-resistant epilepsy and continuous spike-wave in sleep (CSWS) on EEG. Sulthiame starting dose ranged from 0.74 to 6.75 mg/kg/day. Improvement, either in terms of seizure control, cognition, or reduction in EEG epileptiform abnormalities, was reported in 8/16 children (50%). Two patients (13%) became seizure free, while three more (19%) had reduced seizure frequency. Three other patients (19%) had reported improvements in concentration, learning abilities or behaviour. No serious adverse event was reported. Conclusions: These data indicate that sulthiame is effective and well-tolerated in children with CSWS, regardless of the etiology and type of epilepsy.