A surgical guidance device for the precise positioning of a surgical object comprises a base having three feet which define a first plane and which are adapted for location on markers secured to a patient's body. The device includes a swivel head which is constrained for movement in a second plane, and a guide for the surgical object. The guide is mounted on the swivel head so that it can swivel with respect to the swivel head in all directions about a pivot point. The device also includes a locking member for locking the swivel head in a selected translational position in the second plane and the guide in a selected angular position with respect to the swivel head. The surgical guidance device forms part of a kit including three markers securable to a patient's body and on which the feet of the device are respectively locatable.