Navigation services, such as used in cars, are widely used nowadays. Many applications, positioning technologies and techniques have been developed to make navigation systems easier to use. However current navigation systems suffer from different aspects of uncertainty such as incomplete or inaccurate positional data. This paper reviews aspects of uncertainty which should be considered when developing navigation systems. A proposed approach, based on rough set and fuzzy set theories, is explained and implemented in an application. Â© 2012 ACM.