It is shown that the Boltzmann equation of a dilute gas at temperatures above condensation includingLandau's quantum corrections of the streaming term results in a real equation of state. The quantum virial coefficients are given explicitly up to the fourth. A simple prescription for the higher ones is formulated. In the binary collision approximation, which basically underlies the transport equation itself, all virial coefficients can be expressed by correlated products of the real part of the two particle forward scattering amplitude. Averaging these with the free Maxwell distribution at temperatureT one getsB(T),C(T) etc.