The purpose of this study is establish the physiological values of serum colloid reaction and serum enzyme activities representing the liver function. 1,732 industrial workers (1,035 males aged 35-65 yr, and 697 females aged 35-60 yr) were examined by the serum zinc sulfate turbidity test (ZTT) and serum thymol turbidity test (TTT) according to the standard method of "The Japanese society of gastroenterology," serum alkaline phosphatase (ALP) by Kind-King method, serum gamma-glutamyl transpeptidase (gamma-GTP) by the modified Orlowski method, and serum glutamic oxaloacetic transaminase (GOT) and serum glutamic pyruvic transaminase (GPT) by UV method. Then frequency distributions, geometric means, several percentile values of these six laboratory data and correlations among the values were determined. The results are as follows: 1) Frequency distributions of serum ZTT, TTT, ALP, gamma-GTP, GOT, and GPT almost fitted to the log-normal distribution. 2) Geometric means and 0-95th percentile or 5-95th percentile values in bracket were 6.6 (3.7-11.7) Kunkel unit for ZTT in male, 8.2 (5.1-13.0) Kunkel unit for ZTT in female, 0.6 (0-2.8) Kunkel unit for TTT in male, 0.8 (0-2.8) Kunkel unit for TTT in female, 6.6 (4.1-10.4) King-Armstrong unit for ALP in male, 5.5 (3.2-8.9 for 49 year or less, 4.6-10.3 for 50 yr or more) King-Armstrong unit for ALP in female, 15.8 (0-45) mU/ml for gamma-GTP in male, 8.4 (0-17 for 44 yr or less, and 0-20 for 45 yr or more) mU/ml for gamma-GTP in female, 21.4 (0-39) Karmen unit for GOT in male, 20.8 (0-35) Karmen unit for GOT in female, 13.9 (0-29) Karmen unit for GPT in male, and 12.7 (0-32) Karmen unit for GPT in female. 3) Serum ZTT and TTT levels were higher in female than in male. Both ALP and gamma-GTP levels were higher in male than in female, and have become high according to aging in female. Serum level of GPT was higher in male than in female. 4) There were significant positive correlations between serum ZTT and serum TTT levels, and also between serum GOT and serum GPT levels.