This invention relates to an insole which is essentially adapted to the profile of a human foot and has, in the middle foot area, an elastically deformable dome-like arch that faces the foot. To reduce the technical and financial production expense of an insole and to improve the wearing comfort of a shoe through an insole, in particular an insertable insole and to improve the fitting shape of the shoe by means of an insole and to feed air into and out of the shoe interior with the aid of an insole, the insole according to the invention exhibits in the region of the elastically deformable arch at least one ventilation opening, which during walking causes ventilation of the shoe interior in conjunction with the elastically deformable arch.