Purpose: This review is to introduce the performance characteristics of pure tone audiometer specified in the standards and necessary basic calibration instrumentations, explain the electroacoustic calibration among calibration procedures in order to determine if the pure tone audiometer which is being used currently satisfy the standards. Methods: Audiometric calibration consists of three parts; measurement of audiologic equipment performance characteristics, comparison of the measurements to a standard specified in the international or national standards, and adjustment as needed. Calibration checks and adjustments are an essential process for reducing a measurement errors between audiologic equipment and improving the reliability and accuracy of audiologic test result. Results: Specific calibration items that should be checked from audiologic equipment are summarized in International Electrotechnical Commission, International Organization for Standardization, and American National Standards Insti-tute standards. Audiologists should use audiologic equipment which meets appropriate standards and carry out the calibration in order to determine whether the result of calibration check satisfies current standards and exists in the range of a specific tolerances. Reliable test results obtained with audiology equipments calibrated support best audiology practice leading to increased confidence of audiologists. Conclusion: Audiologists have a responsibility to either check its calibration personally or to arrange for periodic calibration of the equipment by an outside service in order to maintain the accuracy of audiologic equipment. For this, audiologists should have proper ability to check whether audiologic equipment meets to the standardized performance characteristics. However, the performance characteristics and calibration methods vary according to the type of audiologic equipment.