[How to scientifically estimate sample size in physiological research].

Objective: To bring about physiological researchers' attention of the importance of sample size estimation.

Methods: The significance as well as the current problems of sample size estimation were illustrated and the commonly-used sample size estimation methods were introduced.

Results: The basic concepts and necessary premises of sample size estimation were stated. The estimation processes and results under two different circumstances were elaborated in detail via examples.

Conclusions: To attain the proper estimated sample sizes, the computation must satisfy the necessary premises which included the appropriate statistical analysis methods to be used.