Abstract: Amaranthus graecizans L. (Amaranthaceae) is reported as a newly recorded naturalized plant in China. The species often exhibits a prostrate habit and is characterized by leaf-blade (particularly larger leaves of main stem) at least 2.5 times as long as broad, narrowly oblong to linear-lanceolate, perianth segments 3, equal or subequal, which is distinct from other Amaranthus species distributed in China. It is native to the Mediterranean region of Europe, northern Africa, and West Asia, and is naturalized in other parts of Europe, East Asia, and Australia, as well as Henan, Hebei, and Shandong provinces of China. This species is easily confused with other species of Amaranthus, so its distribution area in China may be underestimated. Subspecies of Amaranthus graecizans L. and similar species are distinguished here. The relationship between Amaranthus graecizans subsp. thellungianus (Nevski) Gusev and Amaranthus roxburghianus Kung recorded in domestic literature is explained and clarified.