The crucial factor in assessing the indication for implantation of a testis prosthesis is the mental status of the patient. Age and psychosocial considerations must be taken into account. The susceptibility to disturbance following of the loss of a testis differs among individuals. Most of the commercially available products can hardly be distinguished from a normal testis. The findings of a questionnaire in 88 patients with 106 prostheses are presented, according to which substitution of the testis with a prosthesis is not a superfluous therapeutic procedure. The man suffering from his "incompleteness" will be glad to have the implant if it restores to him the feeling of genital intactness. The practicing urologist assesses the indications and answers the questions resulting from emotional and psychic aspects of sexuality. The surgeon selects the appropriate implant and decides on the route of access and type of implantation.