Rubinstein-Taybi syndrome is an extremely rare autosomal dominant genetic disorder that occurs in 1/125,000 and is characterized by distinctive facial appearance, short stature, mild to severe mental retardation, and higher risk for cancer. In addition, variable organ anomalies had been reported. Paraovarian cyst causing torsion of the ipsilateral fallopian tube is less common, with an estimated incidence of 1/1,500,000, but it can adversely affect tubal function. It occurs mainly in women in the reproductive age and is very rare in prepubescent girls. Here, we described the successful treatment of an extremely rare case of paraovarian cyst causing torsion of the ipsilateral fallopian tube in a patient with Rubinstein-Taybi syndrome. A 14-year-old girl with Rubinstein-Taybi syndrome was referred to our hospital for abdominal pain. Her medical history was unremarkable, except for moderate hirsutism and keloid scar. Physical examination revealed tenderness in the lower abdominal midline. The preoperative diagnosis was torsion of a left ovarian cyst. An exploratory laparoscopy was performed because of acute abdominal pain and revealed a left fallopian tube that was twisted twice due to an ipsilateral paraovarian cyst. The huge paraovarian cyst required laparotomy cystectomy, and the left ovary was preserved. Her postoperative course was uncomplicated. Preoperative diagnosis of paraovarian cysts can be difficult. The moderate hirsutism seen in our patient suggested the presence of a large paraovarian cyst due to androgen receptor-mediated effects. Therefore, Rubinstein-Taybi syndrome patients with hirsutism should be screened and assessed by pediatric surgeons for the presence of paraovarian cysts.