Surgical resection is the mainstay in treating acoustic neuroma. But under some conditions no treatment is good treatment is good treatment. These include patients with severe underlying disease that may significantly increase the risk of operation, the elder, tumors in the only hearing ear, contra-lateral ear at risk of severe hearing loss, and small tumors with good hearing. We reported a case who was a 69 years old lady. She was found to have acoustic neuroma on right side no October 1994. During the period of follow-up, the hearing level fluctuated and MRI was used to monitor tumor growth. The volume growth rate calculated in this patient was 0.083cm3 per year and the maximal diameter growth rate 0.317com per year. Since MRI revealed enlargement of the tumor size up to 1.5cm and acceleration of tumor growth, she undertook operation in this August. We removed the tumor via transmastoid translabyrinthine approach.