Some considerations about the zodiacal light brightness integral from the stand point of the theory of integral equations are made. It is shown that for observation directions confined to a plane perpendicular to the ecliptic and passing through the Sun, the Z.L. brightness integral can be formally considered as a first kind integral equation of Volterra type (V.I.E.). In a second step, this equation is transformed into a V.I.E. of the second kind, from which, and under certain assumptions, the spatial distribution of dust out of the ecliptic is obtained.