Motivated to contribute with the guarantee of metrological reliability of electrocardiographs, the present work aims at developing a system for conformity assessment of ECGs, based on the IEC 60601-2-51 standard and on the Metrological Recomendation R-90 (1990) of OIML. Since 1995, the standard series IEC 60601 have been used as base to regulate the evaluation of electromedical equipments in Brazil. The IEC 60601-2-51 standard (performance evaluation of electrocardiographs - ECGs) has been published by IEC in 2003 and incorporated by ABNT in 2005, with the denomination ABNT NBR IEC 60601-2-51. To allow the conformity analysis to the applicable standards, the proposed system was structured in two subsystems: subsystem for electric safety evaluation and subsystem for performance evaluation. The system allows to evaluate analogical and digital electrocardiographs without automated measurements, in agreement with the IEC 60601-2- 51 standard. In order to evaluate the system, it was applied on two digital ECGs in use at a public hospital of Rio de Janeiro. Its calibration, with traceability to SI, has been performed at the Metrology Laboratory of the Electronics Material Depot of the Air Force at Rio de Janeiro (PAME-RJ). The tests performed have shown that the system complies with the requirements of the IEC 60601-2-51 standard. The detected limitations, which were characterized in this work, have simple solutions, concerning the common-mode rejection ratio, temperature drift and reticulate of time and amplitude.