Abstract: The invention concerns locating mobile terminals in a mobile network. A location estimate is determined based on a parameter set received from the mobile network. In order to improve the accuracy of the system, a matrix is formed for an individual first parameter set, the matrix comprising a plurality of elements, whereby each element is associated with a certain geographical area and contains a value which indicates the probability of the mobile being located within said area. At least one matrix formed for a mobile is stored, and in response to a second parameter set received subsequently for the mobile, (a) the values of at least one matrix stored are updated, and (b) the location estimate is determined on the basis of the element values of the matrix corresponding to the second parameter set and on the basis of the element values of the said at least one matrix having the updated values.