The median Venus transterminator ion flux nv(h) derived from Pioneer Venus retarding potential analyzer measurements of the ion velocity and ion density during a period of solar maximum is presented as a function of altitude h from 150 km to the solar maximum median ionopause altitude of 800 km. This flux is integrated with altitude to provide the integrated total ion flux S(h) crossing the terminator plane as a function of altitude. S(h) is nearly a linear function of h, reflecting the nearly constant value of nv with altitude. The value of S at 800 km altitude, called F, is 5¿1026 s-1, a value equal to the total nightside hemispheric molecular ion recombination rate L calculated previously. The loss of ions down the wake of Venus is smaller than F or L by at least a factor of 5. Thus the equality of F and L is evidence that the dominant Venus nightside ionization source at solar maximum is transterminator ion transport. ¿ American Geophysical Union 1992