This chapter presents discussion on opioid analgesics. Previously, the opioids were known as narcotics. Now this term is used only for drugs of addiction. Opioids alter pain perception and thereby alter a person’s reaction to pain. Patient is more comfortable with pain. Associated symptoms such as anxiety, fear, restlessness, tachycardia, sweating, and panic are decreased. There is better tolerance of pain of all types. Methadone is an opioid analgesic. It is not used as analgesic, but is used as substitution therapy in patients with morphine/opioid dependence. Dextromethorphan is an opioid analgesic. It has better oral bioavailability. Pentazocine has prominent action at kappa receptors, hence it mainly produces spinal analgesics. Like morphine it causes sedation, respiratory depression and GIT effects. Pentazocine causes sympathetic stimulation, which may result in tachycardia and rise in BP.