Abstract: A new new formulation tablet B was developed and compared with tablet A with thepurpose of improving the bioavailability of benorilate by rebucing its particle size,The dissolution ratein uitro was determined by paddle method and using surfactant solution medlum, The plasma concentra-tions of hydrulyzates which are salicylic acid and paracetamol from benorilate in vivo were measuted byHPLC. The dissolution rates of ground and unground drug are 0.0337 min-1 and0.0152 min-1(P< 0.001) respectively. Compared with tablet A , the cumulative dissolution percentage of B ishigher. The mean dissolution time of B and A are l5. 77 min and 42.25 min(P<0. 001)respec-tively-The study in uiuo showed that the Cmax,Tp and AUC of salicylic acid for these two formulationshave no significant difference(P>0.1), The relative bioavailability of B to A is l25.59%. Their invivo process fits one-compartment medel and first order elimination.