The tests of dissolution and bioavailability of six formulas of lorazepam tablet under various binders were performed. Lorazepam can be seperated in pharmaceutical preparation and biological plasma by high performance liquid chromatograph. Dissolution process of lorazepam tablet was largely influenced by binder and the dissolution rate was increased by sodium starch glycolate and microcrystalline cellulose, the slower dissolution rate in starch. Bioavailability of lorazepam tablet got relationship with dissolution rate, because tablets containing sodium starch glycolate and microcrystalline cellulose as binder maintained higher plasma level than other binders.