This paper deals with the effects of DDB on human RBC membrane fluidity as reflected by changes in the phase transition temperature and microviscosity monitored by ANS, NPN and DPH. The results showed that DDB decreased the fluidity of the shallow layer (ANS as probe), but increased the fluidity of the middle layer (NPN as probe) and deeper layer (DPH as probe). In addition, the drug was found to inhibit the hemolysis induced by MDA.