A modified ketogenic diet was demonstrated to be remarkably effective in a child with intractable symptomatic focal epilepsy with combined seizures of focal seizures and epileptic spasms (ES) in a cluster (ESC). ES started at 8 months of age and disappeared with ACTH therapy. At the age of 13 months, the child began to have intractable focal seizures that, later, were followed by ESC 10 times a day. Brain MRI showed only a non-specific diffuse cerebral atrophy. Interictal EEG showed high amplitude diffuse disorganized slow waves with prominent sharp waves predominant over the bilateral occipital region. We started a modified ketogenic diet (mKD) treatment without fasting or a water/calorie limitation. Since the 20th day of mKD, the patient has been seizure free (6 months) without adverse effects. EEG showed remarkable improvement and he has some improvement in the developmental milestones. A modified ketogenic diet is easier to start and continue compared to the classic ketogenic diet, and should be tried in intractable epilepsies that are not treatable surgically early in life from the developmental prognosis point of view.