The magnetic structure of small CrO2particles doped with about 1.2 wt.%57Fe has been explored by57Fe Mo¨ssbauer spectroscopy as a function of the particle size. Mo¨ssbauer spectra, obtained with a longitudinal magnetic field applied, unambiguously establish that a noncollinear structure exists that is most pronounced for the smallest particles. The analysis indicates that a surface effect is the origin of this phenomenon. It follows that a core model proposed earlier for the magnetic structure of CrO2small particles is warranted.