The application relates to a method for the mask-etching of a piercing element (14) which has an elongate shaft (16), a distally protruding tip (18), a proximal holding part (20), and a laterally open collecting channel (22) that collects bodily fluid and extends along the shaft (16) as far as the area of the tip (18). For this purpose, a double-sided etching mask (10) is applied to the two sides of a substrate (12) and, under the action of an etching agent, the piercing element (14) is formed as a part made by chemical blanking, wherein a channel side (28) of the etching mask (10) is provided with a channel etching slit (38) for unilateral etching of the collecting channel (22). It is proposed that a proximal and/or distal end portion (40, 60) of the channel etching slit (38) is designed tapering towards the end of the slit.
