Though this publication has not been designed specifically for the marine industry application, we believe that the information contained in it and covering the possible failure that may occur to the bearings could be of some use for marine engineers. We know that if every part of the machinery performed for the whole expected service life, the job of the technicians would be much easier - they would just have to replace the worn parts from time to time, as recommended by the manufacturer of the particular part. But the good mechanic is more that just a replacer of parts, he shall be capable of conducting a proper diagnostics of the machinery in order to determine why exactly the part has failed prematurely. The publication contains a table showing eight most popular causes of the premature failure of the bearings. It shall also be noted that in most of the cases a premature failure occurs due to the combination of two or even more of the causes listed in the table. The authors of the booklet hope that it will serve as a very useful reference manual helping readers to properly determine the cause of the bearing failures; the material is presented in a very readable format and illustrated for easier understanding.