Equipment for drilling secant holes (2) constituted by an excavating system (3, 14, 4, 16, and 17) and by a guide system (7, 8), both of which are set in the hole (2) being drilled and in a previously made hole (2'), the two systems being fixed with respect to one another in such a way as to define a pre-set distance between centres of the holes; the excavating system comprising a rotation means (3) and a bit (4) connected thereto, and being completely introduced into the borehole.