Abstract: 1. Commercial samples of Huo-Hsiang are obtained from ten cities in China. After morphological and histological examinations of these crude drugs, it is proved that they are derived from two plants: one is the dried aerial parts of the genuine Huo-Hsiang (藿香) plant, Agastache rugosa (Fisch. et Mey.) O. Ktze., and the other is the branches and leaves of Pogostemon cablin (Blanco) Benth., the latter is usually sold under the name Kuang-Huo-Hsiang (广藿香) and is cultivated in the province of Kwangtung. In Chinese medicine, Kuang- Huo-Hsiang is generally considered to be superior in quality than the genuine Huo-Hsiang. 2. A brief review of the literature and detailed descriptions of the macroscopical and microscopical characters of the two Huo-Hsiangs are given with illustrations. 3. Some of the more important diagnostic characters of these two drugs are tabulated below: