AbstractThe adenosine to inosine (A-to-I) editing is the most prevalent kind of RNA editing and involves in many biological processes. Accurate identification of A-to-I editing site is invaluable for better understanding its biological functions. Due to the limitations of experimental methods, in the present study, a support vector machine based-model, called PAI, is proposed to identify A-to-I editing site in D. melanogaster. In this model, RNA sequences are encoded by “pseudo dinucleotide composition” into which six RNA physiochemical properties were incorporated. PAI achieves promising performances in jackknife test and independent dataset test, indicating that it holds very high potential to become a useful tool for identifying A-to-I editing site. For the convenience of experimental scientists, a web-server was constructed for PAI and it is freely accessible at http://lin.uestc.edu.cn/server/PAI.