The acronym 'CATCH22' is characterized by many clinical manifestations such as cardiac defects, abnormal face, thymic and parathyroid hypoplasia, cleft palate and hypocalcaemia. It is now known to arise from chromosome 22q11.2 microdeletion, and it is also called 22q11.2 deletion syndrome. Hypocalcemia occurs in more than 50% cases of this syndrome, most frequently in neonatal periods, with some exceptions. Our patient was not diagnosed until age 13, although he had a cleft palate and presented with nasal speech and learning disturbances. He had no clinical manifestations of hypocalcemia until age 13, when he developed generalized tonic-clonic convulsions several times in that year. Laboratory tests showed hypocalcemia, hyperphosphatemia, with normo-to-low parathyroid hormone levels in the serum. Chromosome analysis with FISH revealed a deletion on the proximal portion of the long arm of chromosome 22(22q11.2). The authors herein report a case of CATCH22 syndrome who showed hypocalcemic convulsions in late childhood with a review of the literature.