Kratom is a plant with a long history of traditional use for numerous conditions, often being the drug of choice for self-treatment of pain. The aim of this thesis was to collect relevant preclinical in vivo and clinical studies that investigated the analgesic effect of kratom extracts, its alkaloids (mitragynine, 7-hydroxymitragynine) and semi-synthetic derivatives, clarify the mechanism of action and assess whether it has the potential to become a new legal analgesic. Due to the observed association of long-term use of kratom with the development of addiction, the thesis is based only on the treatment of pain of the nociceptive type. All studies that are included in the thesis confirmed that extracts, isolated alkaloids and their semi-synthetic derivatives of kratom possess analgesic properties. In this systematic review, it was found that the analgesic effects are mediated mainly by the opioid system and that this may become a safety issue in administration. Nevertheless, this thesis offers evidence that there is a potential for one of the kratom alkaloids or a compound semi-synthesized from these alkaloids to become an analgesic that would be more effective and safer than morphine.