In the last two decades it was demonstrated that, in addition to masses and charges, magnetic moments of nuclei are able to influence remarkably chemical reactions. This book presents the physical background (both theoretical and experimental) of the magnetic isotope effects in radical reactions in solutions. Special attention has been paid to the quantitative interpretation of the available experimental data. This book will be useful for physicists, chemists and biologists employing the isotope effect in their investigations as well as for those involved in isotope separation and isotope enrichment projects. Additionally, the magnetic isotope effect appears to be important in geochemistry and cosmochemistry. The book can be recommended for postgraduates and senior undergraduate students.