Résumé : We investigate the effect of a variation of fundamental constants on primordial element production in Big Bang nucleosynthesis (BBN). We focus on the effect of a possible change in the nucleon-nucleon interaction on nuclear reaction rates involving the A = 5 (5Li and 5He) and A = 8 (8Be) unstable nuclei. The reaction rates for 3He(d,p) 4He and 3H(d,n)4He are dominated by the properties of broad analog resonances in 5Li and 5He compound nuclei respectively. While the triple-alpha process 4He(αα,γ)12C is normally not effective in BBN, its rate is very sensitive to the position of the "Hoyle state" and could in principle be drastically affected if 8Be were stable during BBN. We found that the effect of the variation of constants on the 3He(d,p)4He, 3H(d,n)4He and 4He(αα,γ)12C reaction rates is not sufficient to induce a significant effect on BBN, even with a stable 8Be. The main influences come from the weak rates and the A = 2, n(p,γ)d, bottleneck reaction. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.