Abstract Background Clinical practice guidelines and Risk Assessment Models (RAMs) are some useful tools to bring medical evidences into our daily clinical practice. Despite the improvement over the time, they still have some shortcomings. Discussion One of these shortcomings is the arbitrary cutoffs used in these tools to facilitate the decision making process. This problem is to some extent due to the "Black or White" approach of modern medicine in making the decisions, whilst in the real world and our daily practice we used mostly an uncertain approach, which is called recently as "Fuzzy" thinking approach. Summary The authors of this article believe that the fuzzy type of thinking may resolve the above mentioned shortcomings of clinical practice guideline or risk assessment models and they tried to discuss about this using an example about Venous Thromboembolism related guidelines and RAMs.