The chapter gives a brief overview of the principles of operative surgery, diathermy and radiotherapy, along with principles of anesthesia. Every surgeon has his own particular way of doing operations. However, there are some basic rules of operative techniques that should be learnt by the beginners that are regarding skin incision, dissection, wound closure, hemostasis, etc. Factors affecting amount of heat generated during diathermy and practical tips in diathermy use are also listed. Lasers, cryosurgery, high frequency ultrasound waves, and harmonic scalpel are other energy sources used for tissue cutting and coagulation. Radiotherapy is a clinical medical specialty in which ionizing radiations are used to treat cancer and occasionally some benign diseases. Anesthesia in dentistry covers three main types of surgical procedures, namely dental chair anesthesia, day care anesthesia, and inpatient anesthesia. General anesthesia, local anesthesia, regional anesthesia, and central neuraxial blocks are covered in this chapter.