The treatment, research and volunteer work for cleft lip and/or palate (CL/P) has been led for over 30 years by our team. Within this period, more than 4,000 cases of CL/P were treated and at the same time, and approximately 400 papers were published as the first or partner researcher in Nature Genetics, New England Journal of Medicine and others. In addition, with $20 million that was donated from companies and laypeople, and the grant from the Japanese government, CL/P centres in many countries and in Japan, the oral and craniofacial congenital anomaly gene bank in our CL/P centre was established by our leadership. In the bank there are genes from approximately more than 8,000 cases. The genes were mapped with Professor Jeffery Murray of Iowa University in the United States, the findings about genetic syndromes such as Van der Woude Syndrome and basal cell nevus syndrome were applied in clinical settings. The genetic counselling section that specialises in the oral and maxillofacial field was established by our effort for the first time in Japan. In this review, our clinical experience and approach for genetic diagnoses and prevention of cleft lip and/or palate will be discussed. Keywords: cleft lip and palate, epidemiology, genetic study, animal experimental study, prevention