The voyage of the Mexican commission to observe the transit of Venus on 8 December 1874 in Japan is briefly recounted. The five-man expedition was led by Francisco Díaz Covarrubias. They succeeded in establishing two observing stations near Yokohama, one in Nogue-no-Yama and one on a hill called “The Bluff”, and also in determining precise geographical positions for them. Clear skies allowed the observation of the transit at both stations. The results were presented in Paris in 1875, and published on the same year. They were meant as a contribution to be processed along with all other data obtained by different missions. The importance of the expedition for the development of early modern science in Mexico – particularly astronomy – is examined in the broad context of the social and political conditions then prevailing in the country. The relevance of the mission for the establishment of scientific, cultural and even commercial ties between Japan and Mexico is emphasized.