Reductions of four independent blocks of Pioneer Venus Orbiter Doppler radio tracking data have produced very consistent determinations of the GM of Venus (the product of the universal gravitational constant and total mass Venus). These eatimates have uncertainties that are significantly smaller than any values published to date. The value of GM is also consistent with previously published results in that it falls within their one-sigma uncertainties. The value of 324858.60¿0.05 km3/sec2 is our best estimate. ¿ American Geophysical Union 1990