  We investigate two different models. In one of them massive fermions interact
with a massive scalar field and in the other the fermion field is in an
electrical field (QED2). The chiral condensates are calculated in one-loop
approximation. We found that the chiral condensate in the case of the Yukawa
interaction the fermions and scalar field does not vanish if the mass of the
fermion field tends to zero. The chiral condensate disappears in QED2, if the
fermion mass is zero.
