Our investigation shows that in Sichuan Province there are 7 species of medicinal gualou (fruid-rind of Trichosanthes) and its confused fruits (6 species of Trichosanthes and 1 species of Citrullus), among which 2 species are included in the Chinese Pharmacopoeia. The drug and its confused fruits are similar in shape. This paper emphatically deals with the tissue identification of the above mentioned 7 species.