Abstract: A vacuum bushing for an ultracentrifuge that minimizes excessive oil loss due to the high pressure differential across the bushing and allows automatic reclaiming and reusing of a major portion of the uncontaminated oil flow. The bushing is provided with first and second annular chambers, one chamber being connected to an atmospheric oil reservoir and the other chamber being connected to a vacuum oil reservoir. The major oil flow is from the atmospheric reservoir to the first chamber, along the rotor drive shaft to the second chamber, and then to the vacuum reservoir. The vacuum reservoir is connected to the atmospheric reservoir by a one-way check valve so that the oil is automatically returned to the atmospheric reservoir when the centrifuge is deactivated and the vacuum released.