It is desirable for each clinical laboratory to have its own normal ranges. The easy way to obtain them is to utilize the routine laboratory test values. For this purpose many statistical methods have been proposed. In this paper are introduced the three methods, that is, Hoffmann, Neumann and Bhattacharya methods, and a method by the present author based on the maximum likelihood method for estimation of parameters of truncated normal distribution. The author described the statistical principles and the procedures in application about the four methods, and then, applying these methods, estimated normal ranges from the laboratory data on several test items furnished by the clinical laboratory of Busan University Hospital and Busan Gospel Hospital. The 95% normal ranges established by the evaluation of the results by the four methods are as follows: Serum chloride, 91-107mEq/L; serum creatinine, 0.5-1.0mg/dl; serum urea nitrogen, 6-20mg/d1; serum thymol turbidity, 1-7 MU; serum alkaline phosphatase, 3-10 unit (Kind-King) : serum total protein, 6-8g/dl; serum albumin, 3-5gdl ; serum globulin, 1.6-3.8g/dl; blood glucose, 65-105mg/d1. In the process of evaluation of the results it was found that in decreasing order of efficacy are Bhattacharya, the maximum liklihood estimate, Neumann, and Hoffmann method as expected. It is of the author’s opinion that a better estimate of normal range is obtained by using Bhattacharya method together with the maximum likelihood estimate method or Neumann method than by anyone of them, and that Hoffmann method does not, in general, yield good results except in some special cases.