We reported a case of 12-years-old girl with isolated pain in of the left wrist. The problem had lasted for 5 weeks after a trauma, and was getting worse. Wrist X-ray was obtained, and no abnormalities were appreciated. The diagnosis after clinical and echo graphic examinations was a De Quervain's tenosynovitis which has never been reported before in pediatric orthopedic literature. After a four-week immobilization and NSAID usage, the patient was pain free. The excessive mobile phone use with active texting probably increases the problem. Repetitive movements and strain injuries of the thumb and wrist can produce musculoskeletal problems of the upper limb as De Quervain's disease. The purpose of this report is to make the physicians aware of this problem that may be common in the future, especially in the young population.