Background　In recent years, hyaluronic acid has been developed that can be edible, and ingested orally as a dietary supplement that has been reported to the effect of knee pain and other degenerative knee joint disease. However, reports on the safety of oral intake is not need to consider.
Objectives　A placebo-controlled, double-blind study was performed to assess the safety of excessive intake of tablets containing hyaluronic acid in normal healthy adults.
Methods　They were divided into three groups：placebo group（age 37.5±15.4 y.o.）, high-dose group（intake of 24 tablets/day, age 37.8±13.6 y.o.）and standard-dose group（intake of 8 tablets/day, age 37.6±11.2 y.o.）. They were given for 4 weeks. We examined at blood pressure measurement, physical examinations, blood test, urinalysis and interview before the trial, then 2 and 4 weeks after the start of the trial, and 2 weeks after 4 weeks intakes.
Results　Blood pressure, body composition, hematologic and biochemical tests in the blood, which showed some minor variations, was the change in the threshold.
Conclusions　The results demonstrated the safety of excess-intake of tablets containing hyaluronic acid because there were no changes to clinical problems in each test.