The pharmacopoeia monograph for the measles/mumps and rubella (MMR) triple vaccine demands to perform the validation of the potency assay by using the suitable reference material (MR).Aiming at establishing the first work MR (MRT) for the MMR triple vaccine, a national collaborative study was performed with the participation of the two unique national institutions working on the vaccine potency evaluation test, the Imunobiol. Technol. Institute (Bio-Manguinhos, national manufacturer) and the National Institute for Quality Control in Health.The candidate product (cMRTBio) prepared by the manufacturer was evaluated by the participant laboratories by employing the resp. inhouse methodologies for determining the potency.The cMRTBio was considered suitable as inhouse MR, according to the specifications based on the normative compendia, being the intra-assay (< 5 %), inter-assay (< 10 %) and between laboratories variations (< 10 %) below the acceptable limits, and the estimate potency (log10 CCID50/DH) in 3.72 for measles, 4.80 for mumps and 3.70 for rubella.This study reflects the commitment of the unique national MMR vaccine producer to the public health, describing the expansion of technol., the compliance with international guidelines and the careful quality control, leading to the national self-sufficiency in the vaccine production