The influence of metastable atoms on the equilibrium distribution function of an isotropic plasma is studied. It is shown that there is a quasi‐stationary solution to this problem resulting from the balance between electron‐electron interactions, inelastic and super‐elastic collisions. The distribution function is composed of thermal Maxwellian electrons and of a bump at the excitation energy potential of the metastables. Evaluation of the electronic density in this bump is made for the case of helium.