The pharmacology of local anesthesia is considered as the gate to dental anesthesia techniques. In the biomedical field, the human should not be injected with any medication unless the practitioner is well oriented about the nature of the medicine, the mechanism of action, the recommended dose, the maximum allowed dose, and possible complications. In this chapter, the techniques of local dental anesthesia have been discussed in detail as well, including the anatomical landmarks and regional nerve anatomy. The possible local and systemic complications have been added with the proper way of management and percussions. The relation of common systemic diseases to possible complications of local anesthesia medication has been discussed with emphasis on some wrong practioner,s opinion regarding using of vasoconstrictors in hypertensive patient (for details about management of medically compromised patients, read chapter 5, page: 131-195).