At present, there are no generally accepted diagnostic criteria or methods for subclinical hepatic encephalopathy (SHE) associated with liver cirrhosis. We therefore developed an easily conducted computer-aided quantitative neuropsychiatric function test system for use in routine medical practice. We established normal values in healthy Japanese subjects and determined differences between healthy persons and liver cirrhosis patients without clinical encephalopathy in a multi-center clinical trial. The test system consists of eight tests: number connection tests A and B, a figure position test, a digit symbol test, a block design test, and reaction time tests A, B and C. The test results were affected by age, but not by gender or facility. No learning effect was noted. The results were therefore reported by 5-year quartile ranges and differences were evaluated between 542 healthy subjects and 292 cirrhotic patients. When the cut-off value was set at the 10th/90th percentile of the results in healthy subjects, the results of each of the 8 tests were abnormal in about 25% of cirrhotic patients, and at least 1 of the 8 tests gave values greater than the 10th/90th percentile cut-off value in 58.2% of the 292 liver cirrhosis patients. SHE patients were thought to be included in these 58.2% of patients. The developed test makes it possible to quantitatively assess neuropsychiatric function, and the results obtained can be used as a basis for the diagnosis of SHE.