The calculus is performed of the first order perturbations is the motion of one minor planet, produced by another minor planet during their proximity, the conditions begin: the angles between the orbital planes of the given minor planets are under $0^\circ.500$, their proximity (minimum) distances do not exceed 0.000400 AU (60000 km), the perturbing minor planet masses are estimated as being grater than $10^{-13}$ of the solar mass and whose proximity duration is over half a day. The likely perturbing effects indicate that the interactions of the minor planets, taking place during proximity, might well be exploited for a more refined estimates of their masses. It proved that sensible changes appear in $\Omega$, $\omega$ and $M$.