Abstract: In order to study cinnamic acid（CA）stress on root border cells（RBCs）biological characteristic in cucumber and figleaf gourd seedlings，the number of RBCs，viability of RBCs，thickness of mucilage layer of RBCs，the apoptosis rate of RBC and root activities in both species seedlings stressed by 0，0.125，0.250 mmol ? L-1 CA were investigated. The results showed that the number of RBCs，viability of RBCs and root activities inhibited by CA in cucumber seedlings were higher than that in figleaf gourd seedlings. Thickness of mucilage layer of RBC increased was higher in CA treated figleaf gourd seedlings than that in CA treated cucumber seedlings，on the contrary apoptosis rate of RBCs was lower in CA treated figleaf gourd seedlings. For RBCs the same trend was observed in both species stressed by 0.125and 0.250 mmol ? L-1 CA，but the extent of influence by lower concentration CA was lesser than that by higher CA concentration. 0.250 mmol ? L-1 CA inhibited root activities，which were more serious in cucumber seedlings than in figleaf gourd seedlings. Removal of RBCs from root tips led to more severe decline of root activities in 0.250 mmol ? L-1 CA treated cucumber and figleaf gourd seedling，it was more obvious in root activity in cucumber seedlings. It was concluded that RBCs play an important role in protecting root from CA toxicity，especially in figleaf gourd seedlings because of the lower apoptosis rate of RBCs and more thickness of mucilage layer of RBCs.

Key words: cucumber, figleaf gourd, cinnamic acid, stress, root border cell