This paper reports that we can replace a conventional PCB analytical method with an isomer specific analytical method in Yusho diagnosis. The authors analysed 109 blood samples from people who had the 2002 annual inspection for Kanemi rice oil poisoning using both methods. The data from these methods were compared and proved to be almost the same in the so-called "PCB pattern" which has been adopted as a Yusho diagnosis index since early 1970s.