Japanese cedar [Cryptomeria japonica (Thun. ex L.f.) D. Don. (Taxodiaceae)] cultivars have become quite popular in the U.S. landscape and nursery industries. Their popularity is expected to increase as more attractive and adaptable horticultural selections gain recognition. Taxonomic problems include an inadequate inventory of selected variants cultivated in the United States, instability of names at the infraspecific taxonomic level, poor descriptions of the cultivars, and a lack of representative specimens and identification aids to help horticulturists identify unknown specimens. A study of Cryptomeria japonica cultivated in the United States is needed to address these problems.