OBJECTIVE: In 1980s, so-called approved period of disability was imported to Korea from Japan to control the excess of compensation which was caused by an inappropriate rule for disability evaluation. However, there were neither objective criteria nor established area for the approved period of disability. Now, the objectivity and credibility of the disability evaluation become a serious problem. We tried to solve this problem. METHODS: We examined the time of import and background of the approved period of disability. We also investigated the status and problems of deciding the approved period of disability. We used an internet search using the keywords the approved period of disability in the Korean Supreme Court (http://glaw.scourt.go.kr/jbsonw/jbson.do). RESULTS: We found 11 precedents with full text. The approved period of disability was applied only for the disability from spinal injuries at first. The application area became wider. It was used as an expedient to negotiate the indemnities. In 2010, the Korean Academy of Medical Sciences made a new guideline as an appropriate rule for disability evaluation. A new method is necessary for calculating the average or acceptable period of disability instead of the approved period of disability. CONCLUSION: We proposed an ideal method of compensation according to the age and the degree of disability, i.e., (Disability Rate+Age)/5. This formula can be applied when the age was between 21-49 years old and the disability rate was less than 50%.