The genetic variants of the cholinesterase (ChE) are frequently misdiagnosed as a liver dysfunction. We compared three extraction methods for screening of ChE abnormalities. Employing these three methods, total 31 cases were found to be genetic abnormalities from 2985 patients of Hamamatsu University Hospital. We picked up 11 of candidates with low enzyme activities less than 100U/l as group 1 using the first method and effectively detected 9 cases (82%) with genetic abnormalities. The second extraction method was based on the ratio between Albumin (Alb) and ChE and subsequently, 48 of high risk patients were picked up as group 2 and 28 cases (58%) showed genetic abnormalities. Furthermore, all cases of group 1 were contained in the second group. The third method was based on the discrimination function from Alb and total cholesterol (TC) as group 3 and 32 cases were picked up. Fourteen cases (44%) out of them showed the genetic abnormalities using this method, and surprisingly, 13 cases (93%) of them were estimated to be K-variant. Although the three methods showed the different characteristics to extract genetic abnormalities of ChE, the second extraction method could pick up the largest population with genetic abnormalities. Further phenotypic extraction methods should be compared to understand the relationship between phenotype and genotype.