ABSTRACT We report 4 pyridoxine‐dependent epilepsy patients in which good outcome was determined in three. The 4 patients were male and aged from 7 to 24 years old (from three unrelated Caucasian families). A clinical diagnosis of neonatal pyridoxine‐dependent epilepsy was confirmed by biochemical and genetic studies. Clinical evaluation was performed and medical records were reviewed for therapy implementation and management, neurodevelopment outcome, magnetic resonance imaging, and electroencephalography. All were taking pyridoxine treatment and were seizure‐free. Elevated urinary alpha‐aminoadipic semialdehyde excretion was found in all patients. Antiquitin gene analysis identified a large homozygous deletion in one patient and two heterozygous mutations in the others. Treatment with pyridoxine should be attempted for all cases of infantile and childhood refractory epilepsy, as has been the case over the last 20 years. Currently, urinary alpha‐aminoadipic semialdehyde is a reliable biomarker of pyridoxine‐dependent epilepsy, even under pyridoxine treatment. Detection of mutations in the antiquitin gene, encoding alpha‐aminoadipic semialdehyde dehydrogenase, establishes the diagnosis and allows for adequate genetic counselling.