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Abstract. There are several mechanisms by which air affects the infiltration process. In a previous ar-ticle (Morel-Seytoux and Khanji, 1974) only the viscous resistance to simultaneous flow of water and air was considered. In addition there are other effects: the compression effect, the buoyancy effect, the coun-terflow effect, the hysteresis effect and several others. Even though all these effects occur simultaneously it is convenient to treat them at first separately and progressively in partial combinations. In this article the compression effect and then the compression and counterflow effects are added to the viscous resis-tance effect. Formulae for cumulative infiltration versus time are derived. Without the counterflow effect the func-tional form of the equation is similar to that of Green and Ampt with two additional correction terms, one for the total viscous resistance effect and one for the compression effect. With counterflow the de-rived formula no longer has the Green and Ampt functional form. The derived formula remains neverthe-less quite simple. Equation dans le cas de l'infiltration avec l'effet de compression d'air et l'effet de contre-courant Résumé. Dans le cas de l'infiltration dans une colonne fermée, l'effet de compression d'air n'est pas négligeable. Pour des colonnes longues on montre qu'on peut déterminer le taux d'infiltration par une lo