The present study was carried out to study the feasibility of a novel drug-drug solid dispersion for improving the dissolution of poorly soluble drugs. Hydrochlorothiazide - losartan potassium, which is a fixed dose combination and used for treatment of hypertension was selected as a model for the study. Hydrochlorothiazide is poorly soluble and its absorption is dissolution rate limited. Losartan potassium is freely soluble and used to effect solid dispersion of hydrochlorothiazide. Solid dispersion of hydrochlorothiazide-losartan potassium (1:4) was prepared by solvent evaporation method and evaluated by FTIR, X-ray diffraction and DSC analyses and in-vitro dissolution characteristics. The data were compared with that of physical mixture of hydrochlorothiazide and losartan potassium and of pure hydrochlorothiazide. The results showed reduction in particle size, change from crystalline form to amorphous form and enhanced the dissolution rate of hydrochlorothiazide from solid dispersion as compared to physical mixture as well as pure hydrochlorothiazide. The findings of the present study propose that the novel drug-drug solid dispersion approach is beneficial for fixed dose combinations of poorly soluble and soluble drugs to improve bioavailability of poorly soluble drugs.