Abstract:In order to investigate the effect of pycnogenol on immune system,128 male BalB/c mice were divided into 8 groups randomly according to their body weight,16 for each group,every 4 group was considered as one batch for test.Mice in the 4 groups were orally administrated pycnogenol 0,5 0,16 7,50 0 mg/kg BW d -1 respectively for 30 days.One batch were used to observe foot\|metatarsus thickeming (FMT),antibody formation cell (APC),phagocyte function and 50% haemolysis value (HLV).The other was utilized for examination of the activity of natural\|killer cells (NK).The result showed that groups of 16 7 mg/kg BW d -1 and 50 0 mg/kg BW d -1 were found to have significantly increased levels of FMT,APC,PF,NK and HLV than the control.It was concluded that the pycnogenol can enhance the immunological response in BalB/c male mice.