The hemodialysis quality contains the subjective opinions of the physicians. However, the range of good/bad quality of one physician’s perspective usually differs from the others, so we use the fuzzy theory to solve this vague situation. This paper proposes the fuzzy ordered weighting average (OWA) technique to evaluate fuzzy database queries about linguistic or precise values, which can improve the crisp values’ constrains of traditional database. Besides, we deal with the dynamical weighting problem more rationally and flexibly according to the situational parameter α value from the user’s viewpoint. In this paper, we focus on hemodialysis adequacy and develop the query system of practical hemodialysis database for a regional hospital in Taiwan. From the experimental result, we can find the overall accuracy rate is better than other methods and our result is more matching the doctor’s view. That is, the fuzzy OWA query is more flexible and more accurate
