Large magnetoresistance in ferromagnetic transition metals, half-metallic oxides and magnetic semiconductors connected by nanoconstrictions has recently been observed by several research groups. In this work, we present new results that magnetoconductance in nanometer size constrictions has a universal scaling behavior [1]. The results were obtained for half-metallic ferromagnets formed by nanoconstrictions of CrO@sub 2@-CrO@sub 2@ and CrO@sub 2@-Ni. Analysis of the magnetoconductance versus scaled conductance data for all materials known to exhibits so-called ballistic magnetoresistance suggests that the magnetoconductance of nanoconstrictions follows universal scaling. If the maximum magnetoconductance is normalized to unity and the conductance is scaled to the resistivity of the material, then all data points from the current experiment and others in the literature fall into a universal curve that is independent of the constriction material and the transport mechanism. The results agree with a theory that takes into account the enhancement of spin scattering within a magnetic domain wall in nanoconstriction. The adiabatic spin transport increases as the width of the domain wall increases with the size of nanoconstrictions. This analysis suggests that the large magnetoresistance in the nanoconstrictions of materials even in different conductance regimes may have the same mechanism of spin-ballistic transport through magnetic nanoconstrictions. [1] S.-H. Chung, M. Munoz, N. Garcia, W. F. Egelhoff, and R. D. Gomez, Physical Review Letters vol. 89, 287203 (2002). @FootnoteText@ @footnote *@ Supported by the University of Maryland, College Park, NSF and MRSEC, by the Spanish DGICyT, and by the DOE, BES under contract W-31-109-ENG-38.@footnote **@ In collaboration with N. Garcia, M. Munoz, W. F. Egelhoff, H. Pandana, and R. D. Gomez .