This book deals with the Old Testament theme of the vengeance of YHWH, discussing both the exegetical and theological aspects of a biblical notion that until now has received far too little attention in scholarly research.After an exploration of the Umwelt use of the root NQM (vengeance/avenge), in the main part of the study all relevant Old Testament texts are dealt with in a thorough exegetical investigation. This leads to a theological outline which stresses the important place and positive function of God's vengeance in the Old Testament revelation.The theories of G.E. Mendenhall, P. Volz and K. Koch with regard to the theme of vengeance are criticized. Of special interest are the additional sections on the issues of blood vengeance and the imprecatory prayers.