Low level gamma spectrometry is a very precise techniqueto measure the concentration of nuclides present in different samples in Bq kg-1. The quality control of the procedure and method used be carried out by intercomparison exercises with world reconized institutios. During the last three years the Nuclear Physics Laboratory of the University of Costa Rica (LAFNA) has been participating in the international quality assessment program (QAP) carried out by the Environmental Measurements Laboratory (EML), Department of Energy, USA. The results show a very good agreement with the rest of the participant laboratories. This provide a very objetive evaluation of the high precision of the methods used by LAFNA in low leel spectroscopy measurements.