Abstract: A skin pricker is disclosed which comprises a casing (100) and a plunger (132) which fit together telescopically. To trigger the skin pricker, the plunger's head (134) is placed against the skin to be pricked and the casing (100) pressed towards it. A lancet blade (114) is mounted on an element (112) which is integral with a spring (118). The spring is sinusoidal and includes stops (126, 128, 130) for limiting movement of the “waves” of the spring towards one another. Cams (116) carried by the element (112) co-operate with the end surfaces of plates (138) forming part of the plunger so that during initial movement of the casing, the plunger and element move as a unit. When the stops (126, 128, 130) prevent further movement of the element, the cams urge the plates apart and then enter slots (140) in the plates (138). The spring then forces the blade (114) in a forward skin pricking movement. The cams (116) in the plates (138) and can move freely along the slots.