This book about ECG tracings and Holter recordings presented by Drs. Jan and Richard Adamec and Dr. Hein Wellens comprises quite an amazing collection. Each tracing is different from the others and sometimes presents unexplained arrhythmias at first glance. To fully understand these examples, one must understand their peculiarities. Nevertheless, each enigma has a solution, and each case is solved. Comprehension of the different arrhythmias includes their therapeutic consequences; sometimes the best therapeutic option is to do nothing. In studying these cases, it is essential to look very carefully and to understand the pattern of events—first to identify the mechanism, then to determine the clinical importance, and finally to decide whether the case is severe or benign. The classic ECG books, although very comprehensive, do not address this subject the same way. The examples presented in this book are from real-life cases from the practice of Drs. Jan and Richard Adamec and could not be explained adequately in a textbook. These real-life ECG tracings are very helpful because as cardiologists, our goal is to find an explanation for any pathologic tracing. The importance of this book, therefore, lies in its presentation and content, which is composed entirely of tracings from a practice in the Lake Geneva area. These tracings will certainly be of interest to doctors worldwide.