Purpose:To develop the microemulsions system as carrier for treatment of superficial bladder cancer by intravesical administration.Methods:A variety of microemulsions were prepared by using mixture of Tween and Span as surfactant,IPM as oil phase,distilled water as aqueous phase,PG and Ethanol as cosurfactant and CMC and HPC as viscosity-increasing agents.Droplet size and viscosity of the microemulsions were characterized as the physicochemical properties.The gemcitabine aqueous solution and microemulsions of 1% were administered intravesical to bladder of rats (0 h) and kept in the bladder for 1 h by ligating the urethra orifice.The drug concentration in plasma and drug accumulation in the bladder tissue after 0.5,1 and 2 h administration were determined.After the experiment,the histological changes of bladder tissue were evaluated.