To investigate the expression change of BDNF in lamina II of spinal cord from partial deafferented cats, L6 segmentsof spinal cord from 20 adult male cats (5 normal cats, 15 unilateral L6 spared roots cats allowed to survive 3 d, 6 d and 12 d re-spectively) were stained with immunohistochemical technique. The results showed: BDNF positive products were mainly dis-tributed in nerve terminals, varicosities and few neurons of spinal cord lamina II in normal cat. After operation, the density ofpositive nerve terminals and varicosities began to decrease on the third day, reached the lowest level on the 6th day and recoveredto normal level on the 12th day on operated side. But the number of BDNF neurons showed no obvious change. The authors sug-gest that the decreased density of BDNF positive products in lamina II on the 3rd and 6th day was related with the degenerationof the nerve fibers and varicosities after section of the adjacent dorsal roots. On the 12th day, the remaining L6 dorsal roots un-derwent collateral sprouting compensatoryly and reestablished functional connection with target neurons. Therefore, BDNF maybe involved in the normal physiological function and the plasticity of spinal cord after damage.