A review is given of theoretical and experimental research in the new field of magnetic resonance in the case of overlap between nuclear and electron spin resonance frequencies in magnetically ordered media. Particular attention is devoted to the typical (for magnetic materials) situation in which the electron relaxation parameter is much greater than the dynamic electron-nuclear interaction parameter. Both stationary and transient phenomena are considered. Recently discovered new effects in the overlap region are examined in detail. It is shown that NMR signals can be detected by simple ferro- and anti-ferromagnetic resonance methods.