In general, it is easier to detect that some sort of damage has occurred in rolling element bearings than to accurately assess damage severity and the risk of failure if no replacement is done when using vibration-based maintenance. When the vibration level of a rolling element bearing is increasing, close to or greater than the predetermined replacement level, the assessment of the probability of a bearing's failure enhances the decision making process. Thus, at each vibration measurement a decision has to be made regarding whether the bearing needs to be replaced and how urgent it is actually. The paper describes a graphical method for both assessing the probability of failure of damaged rolling element bearing and predicting the residual of its effective life. It uses history of the bearing in question and life statistics as well as the vibration levels at failure/condition-based replacements of past bearings of the same design or very similar performing and duties. This method is based on the concept of Total Time on Test, M-plot. The application of TTT-plot on age and condition-based maintenance techniques are discussed and two examples are presented. This graphical method is developed from previous work by the author and others.