Vitamin B6 (VB6) is used frequently as one of the first-choice drug for the treatment of West syndrome (WS) in Japan. We report 2 cases of symptomatic WS who had a good response to readministration of VB6. Case 1 was a 3-year-old girl diagnosed as having severe hydroencephalus. She developed WS at the age of 9 months. She was treated with ACTH, but relapsed when she was 1 year old. Despite treatment with various conventional drugs and second ACTH therapy, her seizures were not suppressed. We reviewed past treatment records in another hospital, and found that VB, treatment was stopped because her EEG did not improve within a week. We then retried VB6 therapy when she was 3 years and 6 months old, and as a result she became seizure-free and hypsarrhythmia disappeared on EEG within a month. Case 2 was a boy with severe cerebral palsy who was diagnosed as having WS at the age of 9 months. His MRI revealed bilateral subdural hematoma. Treatment was started with VB6, and he became seizure-free within several days. But 7 days after starting VB6, treatment was stopped because of the side effects. VPA was started instead, but his EEG showed gradual worsening. Then, we added a smaller dose of VB6 to VPA. His EEG improved dramatically, and his seizures have been controlled without any side effects. The present cases indicate the possible clinical usefulness of successful VB6 retrials even in older patients with severe organic lesions, by means of combined therapy with other drug, and alternative design of the dosing. However, we suspect there might be many cases in which the efficacy of VB6 therapy has not been properly assessed due to the short observation period and/or side effects.