Apparatus for sampling blood by puncturing a skin through which the blood can be obtained, includes a housing (2) providing a surface against which a human thumb (22) can be placed. An aperture (6) in said surface communicates with a chamber defined by the housing (2). A needle (20) is supported in said chamber. The base of the housing (2) is dome-shaped for imparting to the needle (20) when pressed beyond its point of inversion an acceleration in the direction of the aperture (6) to propel said needle (20) though the aperture (6) to puncture the skin, and subsequently to withdraw the needle (20) from the skin to enable blood to pass through the punctured skin into the chamber.
