The Goslon Yardstick Japan Seminar, a training course for the evaluation of dental arch relationships in patients with unilateral cleft lip and palate was held in April 28th-30th, 2009 in Tokyo. In this course, Dr. Michael Mars was invited as a lecturer from the Great Ormond Street Hospital in London, UK. The number of delegates was more than one hundred from a wide variety of specialist. As this was a training course, it was considered that there were large biases in the selection of models evaluated. The result showed that the dental arch relationships in Japanese patients were not so good in total. However, better results were found in some hospitals. We hope that this seminar would contribute to the improvement of the treatments for patients with cleft lip and palate.