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Chromosome 22q11.2 deletion syndrome is the most common interstitial deletion syndrome. Major clinical manifestation includes hypocalcemia secondary to hypoparathyroidim. At least 10 % of the patients with this syndrome had hypocalcemic seizures which are generally improved over the first year of life because of the increase of parathyroid gland hypertrophy and dietary calcium intake. We present two cases of this syndrome diagnosed in 12-year-old boys with new onset hypocalcemic seizures. This case report hopes to call attention to this syndrome as a potential cause of hypocalcemic seizures even after the neonatal period. Furthermore, our first patient showed inheritance from a paternal deletion which is not as common as maternal deletions. This is the first case report of hypocalcemic seizure with a paternally inherited 22q11.2 deletion in Korea. (2012;2:43-47) Key words: Chromosome 22q11.2 deletion syndrome; Hypocalcemia; Seizure; Paternal; Inherited Chromosome 22q11.2 deletion syndrome is the most common interstitial deletion syndrome, with an incidence of 1 in 4000-5000 births and approximately 5-10 % with inherited deletions.1 Initially, this condition was referred to as CATCH22, the acronym of cardia