[en] A comparison is given of the luminosities achievable with the proton-antiproton collision schemes proposed by CERN and by Fermilab. Estimates have been made by both CERN and Fermilab groups but these estimates have not been made with a consistent set of assumptions. A comparison of the potential performance of the two schemes at present is therefore not possible. A realistic assessment of the many details entering is needed, and a deep understanding of the factors contributing to the luminosity may lead to improvements which in turn could result in increased luminosity. Using the antiproton schemes proposed, it is found that the luminosity at 1000 GeV/c of the Fermilab Doubler as a antip-p collider is 3.4 x 10²⁹ and the luminosity of the SPS at 270 GeV/c as a anti p-p collider is 1.0 x 10³⁰