A customized drilling jig for implantation of a hearing aid involves a molded imprint (14) of a patients upper teeth (12) made of a solidified elastic material connected to a jig (16) having a lateral beam (20) and navigation benchmarks (22) and with which a three-dimensional image of the patients head can be captured for determining a minimal invasive drilling axis (28) for hearing aid implantation based on the three-dimensional image. The customized jig has a drilling guide opening in a lateral beam of the jig for guiding a drilling tool (26). The position and orientation of the drilling guide opening are selected to guide the drilling tool along the determined minimal invasive drilling axis when the jig is positioned on the patients head by using the imprint (14).
