Magnetic resonance imaging (MRI, magnetic resonance tomography - MRT, nuclear magnetic resonance - NMR, English: Magnetic Resonance Imaging - MRI) is a modern non-ionizing, noninvasive radiological methods of examination which visualize and diagnose anatomical, morphological and functional state of the organs of the human body. MRI is the only one of the important radiological information system. The work of MR is based on the application of a strong homogeneous magnetic field and modern computer technology. This paper presents the basic MRI, history of MRI, magnetic field strength in MR, MR physical principles, principles of MR and MR sequences. Conclusion: MRI is a sovereign, dominant and non-ionizing radiological examination method, which are enriched radiological imaging techniques of pathological states authority, and whose work requires appropriate knowledge of physics, medicine and computer science.