To investigate the effects of stereological alteration of platelets on hemorrhage in hemorrhagic fever with renal syndrome(HFRS), platelet mean cross area(A), area density of alpha-granules(Na), volume density(Vv), the mean open tubule(OCS) and pseudopodia mean(M) were performed stereometric analysis in 12 patients with HFRS. The platelet A was observed, and no significant difference was found compared with the control(P > 0.05), while the number of pseudopodia M was higher, and the open tubule number was lower than those of the control(p < 0.01). The results suggest that in addition to the total platelet count decrement, the quality deterioration and functional activity abnormalities of platelets play an important role on the disordered hemostasis and coagulation in HFRS.