The interaction between salicylic acid and bovine serum albumin has been studied by fluorescence spectroscopy. The results show that the quenching mechanism of the combination of bovine serum albumin with salicylic acid is a static quenching procedure, the quenching constant K(sv) is 1.097 x 10(4) (mol x L(-1))(-1), and the equilibrium constant is 7.377 x 10(4). The number of binding sites is 1 and it is a strong one. When the ratio of molar concentration of salicylic acid to bovine serum albumin is lower than 1:1, it binds to Trp residue first but it doesn't result in any microenvironment changes of Trp residue. The binding distance between salicylic acid and bovine serum albumin and the energy transfer efficiency were obtained based on the theory of Förester spectroscopy energy transfer.