A semisolid gel of diclofenac potassium was formulated with carbomer and other excipients. The contents of diclofenac potassium gel were determined by HPLC. The average recovery was 99. 55% , and RSD=1. 22%. Compared with Votalin gel the results show that the diclofenac potassium gel has an anti-inflammation action on metatarsal swell treated by carrageenin.