The invention relates to an adapter for testing printed circuit boards and to a testing needle for such an adapter. The inventive adapter is characterized by two units that can be displaced with regard to one another, whereby each unit has one or more guide plates. The guide plates are provided with guide borings. The guide borings of the guide plate of a unit are respectively arranged in the same pattern. These patterns correspond either to the pattern of the printed circuit board test points of a printed circuit board to be tested or correspond to the pattern of testing contacts of a basic grid of the testing device. When fitting the adapter, both units are displaced such that the guide holes corresponding to a testing needle are aligned with one another so that the testing needles can be fitted into the adapter in a manner that is perpendicular to the guide plates. This fitting process consisting of displacing the adapter units and of introducing the testing needles is repeated until the entire adapter is fitted. A fixing device is provided for fixing both units into a zero position, in which all guide holes of one of the two units have a minimum offset with regard to the corresponding guide holes of the other unit so that all testing needles are retained in the adapter by frictional contact. |