Pain primarily has the role of protecting the body because it is a kind of alarm and very often pain is the first symptom and reason why the patient seeks medical help. The mechanism of pain is a very complex, and the very perception of pain depends on different factors that differ in each person. The path of spreading a painful stimulus from the site of injury to the brain is known as the pathway, and consciously experiencing pain is called nociception. According to anatomy and neurophysiology, the pathway is divided into four phases - transduction, transmission, modulation and perception. Pain can be assessed using a variety of one-dimensional and multidimensional scales to assess pain intensity. We can use various pharmacological and non-pharmacological methods to treat pain. In pharmacological ways, there are a number of drugs that are administered depending on the intensity of the pain. The approach of treating pain most often uses a three-step scale developed by the World Health Organization (WHO). It recommends that in mild pain a non-opioid analgesic is used, in moderate pain a weaker opioid analgesic (possibly with a non-opioid analgesic), and in severe pain a strong opioid analgesic. The strongest analgesics are opioids. Opioid analgesics are used in the treatment of very severe or chronic pain and they act through μ, κ, and δ receptors. The effects of opioids are euphoria, sedation, and immune system stimulation, but the most important is analgesia that is common to all three receptors. This thesis will analyse the use of opioid analgesics used in 2019 in the Department of emergency medicine of Zagreb county. The Department of emergency medicine of Zagreb county uses morphine and tramadol as opioid analgesics to suppress severe and very severe pain. The use will be analysed according to gender, age, type of pain (acute or chronic), different ways of drug application and frequency of concomitant use of antiemetics in the case of intravenous opioid use. Data from 2019 will be analysed retrograd thru all 8 EMS units of the Zagreb County Institute of Emergency Medicine by inspecting the electronic database e-Hitna.