Abstract: Blood letting apparatus is disclosed which is particularly adapted for operation by the patient, the device being characterized by a substantial reduction in the pain of administration and by the provision of an efficient release of blood with minimal admixture of tissue fluids. A feature of the invention resides in the provision of a lancet carrier for removably receiving disposable sterile lancets and a hammer member for activating the carrier, the carrier being free of connection with the hammer whereby the point of the lancet may be disposed against the skin of the user in advance of the carrier being struck by the hammer.