Seizures are common in hyperglycemia and are often the first manifestation particularly in non-ketotic hyperglycemia (NKH). Published reports emphasize partial motor seizures almost exclusively. Here we present the clinical, biological and electrophysiological features of 22 consecutive patients with NKH who developed focal seizures and were treated in our department. Neurological exam was normal in 15 cases. When abnormal, it showed postictal obnubilation or diabetic polyneuropathy. Interictal EEG (obtained in 17 patients) showed focal or generalised slowing in 65% of cases, and ictal EEG (six patients) showed rapid spikes most often unilateral. CTs were normal in 77% of cases, and showed age-compatible cortico-subcortical atrophy in the others. All patients were alert, with glucose values between 13.6 and 55 mmoles/l and osmolarity values increased in all cases to a mild or moderate extent (266-309.20 mosm/l). Three out of 22 patients (14%) presented with motor epilepsy partialis continua. In 11/22 cases (50%), diabetes mellitus had not been diagnosed previously. Seizures associated with NKH were resistant to anticonvulsant treatment but responded well to insulin therapy and rehydration. They subsided completely in an average of 4 days, and only one patient had to be transiently transferred to ICU. We conclude on the importance of an early diagnosis of this condition to prevent malignant evolution of the epileptic syndrome into a state of hyperosmolarity and coma associated with a much higher mortality.