Finding patterns from data sets is a fundamental task of data mining. If we categorize all patterns into strong, weak, and random, conventional data mining techniques are designed only to find strong patterns, which hold for numerous objects and are usually consistent with the expectations of experts. While such strong patterns are helpful in prediction, the unexpectedness and contradiction exhibited by weak patterns are also very useful although they represent a relatively small number of objects. In this paper, we address the problem of finding weak patterns (i.e., reliable exceptions) from databases. A simple and efficient approach is proposed which uses deviation analysis to identify interesting exceptions and explore reliable ones. Besides, it is flexible in handling both subjective and objective exceptions. We demonstrate the effectiveness of the proposed approach through a set of real-life data sets, and present interesting findings.