The magnitude of the rodent problem in Europe has never been evaluated in detail due to many factors. First of all the assessment of rodent damage is very time consuming and difficult to carry out, whether the damage is inflicted to crops or to structures. The significance of rodents as carriers and transmitters of diseases has, apart from a couple of well-known bacterial diseases (leptospirosis and salmonellosis), not been thoroughly investigated. In the following, the various problems created by the most common rodent species are briefly described, with the main emphasis on field rodents.