In this work, a comparative study of neutron activation analysis (NAA) was performed by the nuclear institutes: CDTN/CNEN-Brazil, CCHEN-Chile and the SCK.CEN-Belgium aiming to investigate some generic, manipulated and reference medicines largely commercialized in Brazil. Some impurities such as: As, Ba, Br, Cc, Co, Cr, Eu, Fe, Hf, Sb, Sc, Sm, Ti and Zn were found, and the heterogeneity of the samples pointed out the lack of an efficient public system of quality control. (c) 2008 Elsevier Ltd. All rights reserved.