Phlebotomy - the drawing of blood - is essential for medical diagnostics, but there are problems with inconsistent sample quality, complications and high operational costs. Automation of the phlebotomy process may solve these problems; however not all steps of the phlebotomy process are currently automated. Automatic vein detection and needle puncturing have already been developed, but the tourniquet, a device used to cease the flow of blood, still needs to be automated. This study aims to design and evaluate an automated tourniquet for a fully-automated venipuncture device. In this study, two concepts were explored. The elastic tourniquet uses a strap tightened by an electric motor. The pneumatic tourniquet uses an air filled bladder, which is inflated to a standardized pressure. Both prototypes were realised and verified according to the system requirements. After verification a validation was conducted with seventeen participants, to determine usability and test user requirements. The participants used both prototypes and scored them on ease of use, comfort and sense of safety. Both prototypes did not meet three out of nineteen requirements during verification, but the shortcomings were deemed only minor. Both prototypes were considered easy to use, reasonably comfortable and instilled subjects with a high sense of safety. The pneumatic prototype scored slightly higher on comfort and safety. Users were able to apply the elastic tourniquet significantly faster and less mechanical noise was produced during operation. This study shows that it may be possible to implement automated tourniquets in fully-automated venipuncture devices in the near future. I conclude that the elastic prototype is best suited for automated phlebotomy. The shortcomings can be solved with little difficulty, whilst the design is less complex and more scalable. For this, I recommend performing clinical device testing to validate the performance of this novel tourniquet concept.