This letter studies the intrinsic variability in oxide-based resistive RAM technology, highlighting the presence of a short range ( $\approx 40$ ) correlation of resistances among cycles (for both low resistance state and high resistance state). Experimental results demonstrate the existence of a resistance correlation, and an analytical model is proposed in order to explain the findings. The presence of the correlation seems to indicate that the conductive filament, which is believed to be the basis of resistive RAM behavior, keeps for a limited number of cycling operations a memory of its morphology. The extension of this correlation depends on the programming conditions.