Abstract Introduction In the current scenario, in which evidence-based medicine is almost obligatory, therapeutic approaches are increasingly being restricted to measures that are proven to bring benefits to the patient. Transfusion therapy follows the same concept. Even though it can be an essential support procedure in some situations, it must be carefully used, exclusively in situations in which the literature assures scientific support for its usage. Transfusion exposes patients to risks and complications, so it is necessary that we, as doctors, continue working to reduce possible mistakes involving the practice of this type of therapy. Objective To analyze if the red blood cell requests are properly made, analyzing the indication written on them (by the doctor, comparing them to the references in the actual literature. Method In this research, we have analyzed and reviewed the requests for red blood cell concentrates between August and September of 2018 received at the Hematology and Hemotherapy Center studied to find the most common mistakes made by requesters/doctors. Results A total of 397 of the 754 analyzed requests were evaluated as inadequate. Therefore, 1 out of every 2 transfusions performed did not have their requests properly completed in the city of Cascavel, Paraná. Conclusions The number of inappropriate requests was high during the studied period, especially when compared to studies available in the literature. The number of inadequacies suggests that the blood component requests and the subsequent evaluation by the transfusion agency needs to be better addressed in clinical practice.