Background: In intensive care units, blood sampling is done commonly as part of daily routine. It remains unknown whether this practice is associated with harms or benefits, as not all routine blood tests may be clinically indicated, and blood sampling done without specific indications may be problematic. Accordingly, we aim to assess the body of evidence regarding the usage of routine vs on-demand blood sampling in critically ill patients in a scoping review. Methods: We will conduct a scoping review in accordance with the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) statement as well as the PRISMA Extension for Scoping Reviews (PRISMA-ScR). Using a PICO-based search strategy, we will systematically search the Cochrane Library, Embase and Medline for relevant studies regardless of design. Two authors will independently screen studies for inclusion and extract data. We will provide a descriptive analysis of the data and asses the quality of evidence in accordance with the Grading of Recommended Assessment, Development and Evaluation approach. Discussion: The outlined scoping review will provide an important overview on the current body of evidence regarding the use of daily routine vs on-demand blood sampling in critical care settings. The findings of this scoping review will guide further research.