|Aim: SCENIC recommendations for surveillance colonoscopy in ulcerative colitis (UC) have accepted the application of Japanese macroscopic classification for UC-associated neoplasia. The aim of this investigation was to examine the application of Japanese magnifying colonoscopic classifications for UC-associated cancer/dysplasia. Method: We retrospectively reviewed colonoscopy records from 2009 to 2016 at our institution and identified cases of endoscopically or surgically resected UC-associated cancer/dysplasia observed by magnifying colonoscopy. Cases were classified by JNET classification for magnifying narrow-band imaging and by Kudo-Tsuruta pit pattern classification for magnifying chromoendoscopy. Magnifying colonoscopic findings were compared with histological diagnosis and invasion depth. Results: UC-associated cancer/dysplasia comprised 3 dysplasias, 6 intramucosal cancers, 4 cancers with massive submucosal invasion and 1 cancer invading the proper muscular layer. Among 14 subjects, type 2B of JNET classification trended to be more frequent in cancer compared to dysplasia (90.9%[10/11] vs. 33.3%[1/3], respectively, P=0.09). The diagnostic sensitivity, specificity, and positive predictive value (PPV), negative predictive value (NPV) and accuracy of type 2B, or 3 of JNET classification for differentiating cancer with massive submucosal invasion or proper muscular layer from dysplasia or intramucosal cancer were 100%, 33.3%, 45.5%, 100% and 57.1%. The diagnostic test values of VI high irregularity/VN of pit pattern classification were 40%, 100%, 100%, 75%, and 78.6%. Conclusions: Type 2B and VI high irregularity/VN can be applied to the histological diagnosis and invasion depth of UC-associated cancer/dysplasia.