Here we present a case of a coincidence of addiction to "Kratom" (botanically known as Mitragyna speciosa Korth) and developed severe primary hypothyroidism. We are discussing a possibility that high dose of indole alkaloid mitragynine (the major alkaloid identified from "Kratom") might reduce the normal response of the thyroid gland to thyroid-stimulating hormone resulting in primary hypothyroidism. Further experimental investigations of mitragynine as a possible suppressor of thyroid gland function would be a matter of interest.