The case of a 5-month-old boy with tuberous sclerosis and West syndrome is reported. Tonic spasms were noted from the age of 4 months. High-dose pyridoxal phosphate could not control the seizures completely. Very short and low-dose adrenocorticotropic hormone (ACTH) therapy (i.e. 0.011 mg/kg per dose, 12 times in 20 days) controlled the seizures, while pyridoxal phosphate was on. Early tapering of ACTH was successfully done while abnormal electroencephalogram (EEG) findings remained. Although side effects such as hypertension and brain shrinkage were transiently observed, both the cognitive and seizure prognoses were excellent at the age of 3 years and 2 months. The good response to a small dosage of ACTH might be due to some responsiveness of the high-dose pyridoxal phosphate and the underlying cause of tuberous sclerosis with normal development before onset. The present case illustrates that the duration and dosage of ACTH therapy in West syndrome should be modified according to the individual's requirements.