An NMR probe head (3) has a coil system (9) and a radial centering mechanism for a sample vial (4) having two centering devices spaced axially from each other to center the sample vial in the radial direction only. The first centering device (5) is disposed above the receiver coil system and at least one further centering device (6) is disposed axially above the coil system with an axial spacing (d) above the first centering device. The first and second centering devices restrict the radial scope for movement of the sample vial to such an extent that the sample vial cannot touch an endangered space (7) during the entire duration of transport of the sample vial to its measuring position, thereby precluding damage to the probe head components in the endangered space by the sample vial.