Magnetic resonance imaging (MRI) is relatively safe imaging modality that does not involve ionizing radiation and is used for diagnostic purpose; it involves both static and time varying magnetic fields, beside RF electromagnetic waves. MR imaging applied to living tissues provides a promising new technique for medical imaging but there were no clear demonstration of MRI biological effects. This book review number of scientific researches and studies on that points and also it presents an experimental work that assess the hematological and histological effects of the electromagnetic radiation used in the MRI as repeated exposure effects on different blood parameters .This book also pressed on the safety considerations in MR imaging when the examinations were applied. So this book provides knowledge about the biological effects for Diagnostic Radiologists and Technologists.