The effect of preferential concentration of heavy particles in ahomogeneous stably stratified turbulent flow is studied by means ofdirect numerical simulations. Particle distributions show differentclustering patterns in horizontal and vertical directions, therebyrepresenting the anisotropy of the flow. Preferential concentration instably stratified turbulence can be quantified using 2D and 3D radialdistribution functions and the correlation dimension D_2. Withincreasing stratification strength, the effect of preferentialconcentration decreases. Furthermore, it is found that in stablystratified turbulence preferential accumulation is enhanced whengravitational forces act on heavy particles.