The term kratom is commonly used for both Mitragyna speciosa and herbal products prepared mainly from leaves. Kratom is well known as a drug that can serve as a less toxic and less-addictive pain-relieving substitute for opium, as well as a therapy for hypertension, cough, and diarrhea. Its major alkaloid, mitragynine, also deserves concern. However, most people use kratom as a psychological stimulant, which carries a risk of addiction associated with negative social and health impacts. This paper reviews basic facts about kratom and its potential use in pharmacology, pharmacokinetics, and pharmacokinetics of its major alkaloid mitragynine (Tab. 3, Fig. 1, Ref. 87). Keywords: 7-hydroxymitragynine; alkaloid; anesthetics; antitussive; drug; mitragynine; Mitragyna speciosa; addictive substance; opioid receptor.