Abstract: A blood sampler comprises a small chamber having a stiletto mounted air-tightly through a flexible top wall with a pointed end of the stiletto positioned inside the chamber opposite an opening in the bottom part of the chamber. The sampler is designed to be mounted in a tool which compresses the chamber by pressing the flexible top wall against the bottom of the chamber. Further, the tool has means for imparting an impact on a blunt outer end of the stiletto to drive the stiletto further through the top wall to make its sharp end protrude through the opening in the bottom part into the skin to which the sampler may be attached by an adhesive. When the sampler is ejected from the tool, it regains its original shape, providing in the chamber a vacuum for sucking blood from the perforated skin into this chamber.