The coexistence of gonadotropin-releasing hormone (GnRH)-dependent sexual precocity and growth hormone deficiency in patients with arachnoid cysts is rarely reported, and its pathogenesis is not well recognized. This report describes an 11-year-old female who had a huge intracranial arachnoid cyst with initial symptoms and signs of sexual precocity. Her brain magnetic resonance imaging revealed distorted hypothalamus with a thin and stretched pituitary stalk. After treatment with cysto-peritoneal shunting and gonadotropin-releasing hormone analogue, her puberty was arrested and subnormal growth rate was observed. Catch-up growth was detected after growth hormone therapy. Hence, coexistence of gonadotropin-releasing hormone-dependent sexual precocity and growth hormone deficiency in this patient was confirmed.