The invention relates to a method for making a surgical guide (1) for performing bone harvesting (O), including: « Generating a three-dimensional image (20) of at least one portion of a bone of a patient (Pa) where said harvesting is to be performed, said bone defining an outer surface (4)； · Identifying in said three-dimensional image (20) one or more sensitive anatomic structures (21) that must not be involved in said bone harvesting； Identifying in said three-dimensional image (20) a volume (30) of bone suitable for being removed in said bone harvesting, said volume excluding said sensitive anatomic structures, and said volume being delimited by a portion (6) of said outer surface (4) of said bone defining a perimeter (31) and by a mantle (38) extending from said perimeter inside said bone, said mantle including, for each point of said perimeter, a segment forming a predetermined angle (a,b) with said portion of outer surface, said angle corresponding to a cutting direction (L1, L2, L3, L4) inside said bone identified in said three-dimensional image； Designing said surgical guide (1), said guide defining a guide surface (8) suitable for being rested on said outer surface (4) of said bone, said guide surface comprising a work area (2) delimited by guide walls (5a,5b,5c,5d), said work area having a perimeter (3) corresponding to the perimeter (31) of said portion of surface (6) of said bone identified in said three-dimensional image； Angling at least one of said walls with respect to said guide surface (5a,5b,5c,5d), so that said wall includes a face (7a,7b,7c,7d) that constitutes a geometrical extension of a portion of said mantle (38) of said bone volume (30), when said guide is rested on said outer surface of bone, so that said face includes, for each point of said perimeter of work area, a segment forming a predetermined angle with respect to said guide surface.
