Comprehensive measurements of electron spin resonance (ESR) and magnetization of La0.7Ca0.3MnO3 in the ferromagnetic as well as paramagnetic phases were carried out. Quantitative evidences for the inhomogeneous magnetic structure, consisting of ferromagnetic microregions embedded in the antiferromagnetic surrounding near T-c, were found. It is suggested that the microscopic local magnetic structures above and below T-c are qualitatively similar except that the phase below T-c carries long range order between the ferromagnetic microregions whose sizes grow with decreasing temperature. (C) 2002 Elsevier Science B.V. All rights reserved.