[en] Full text: Several intercomparison exercises were organized by the International Atomic Energy Agency (IAEA) on the determination of operational quantities at the regional or interregional basis. These exercises revealed significant differences in the approach, methods and assumptions, and consequently in the measurement results obtained by participating laboratories. In the Latin America region, an intercomparison for determination of operational quantity Hp(10), organized within the frame of a technical cooperation regional project, was completed mid-2004, as a follow-up to previous exercises carried out during the 1990s. Eighteen laboratories from 19 member states participated in the first phase; the second phase grouped 15 laboratories from 16 member states. Dosimeter irradiations (5 different radiation qualities for photon simulating workplace fields) were done by 4 Secondary Standards Dosimetry Laboratories (SSDL). The preparations for the exercise involved an audit by the IAEA SSDL, where reference irradiations were provided to all participants for verification of their system. During the first phase (2002/03), only 9 out of 18 laboratories met the performance requirements for such monitoring services. Necessary corrective actions and procedure verification were implemented, and staff involved in these evaluations were subsequently trained. During the second phase (2004), 11 out of 15 laboratories fulfilled the performance criteria. The 4 laboratories still having difficulties in assessing occupational exposure participated in a results meeting, during which problem areas were identified. An ongoing technical cooperation mission is expected to assist these laboratories accordingly. There has been a definite improvement in the second phase and most laboratories demonstrated a good performance in the quantity tested. The technical results clearly show that the laboratories' capability in assessing occupational exposure from external sources of radiation is adequate. These results underline the importance of such an intercomparison programme as a key element towards the harmonization of quantities and units on an international level. This paper presents the intercomparison results. It must be noted that member states strongly recommend that the IAEA continue acting as a focal point for, inter alia, training in all forms, particularly in measurements and dosimetry techniques. This exercise also stressed the importance for the IAEA to take an active role in establishing a network of monitoring laboratories for radiation protection purposes, as it would provide for better information exchange for similar projects. (author)