Systems to stratify difficulty of laparoscopic liver resection (LLR) are useful and they are essential for safe LLR. The IWATE scoring system (IWATE criteria) was proposed after the discussion at the 2nd International Consensus Conference on Laparoscopic Liver Resection with modified from the original difficulty scoring system for LLR. The IWATE criteria is useful to predict the difficulty of LLR and intra- and postoperative outcomes as well. To date, there were five proposals of difficulty of LLR. In the original “difficulty scoring system”, grading by tumor location, extent of liver resection, tumor size, proximity to major vessel, and liver function was previously validated and strongly associated with intra- and postoperative outcomes by Japanese multicenter analysis. Tomassini, et al proposed difficulty classification into 10 scales from partial resection of segment 3 and 4b (scale 1) to mesohepatectomy and left trisectionectomy (scale 10). This classification was proposed based on 4 European experts’ experience for surgeon’s learning curve. IMM group classified difficulty into 3 groups (11 procedures) according to operation time, bleeding, and conversion rate. The 3 groups were associated with postoperative morbidity rate. Hasegawa et al, proposed a classification system in which grading was decided by extent of resection, location of tumor, obesity, and platelet count. The grading was associated with intra- and postoperative outcomes. These five proposals of difficulty of LLR will be discussed.