A method, system and computer program product are provided for implementing PCI-Express memory domains for single root virtualized devices. A PCI host bridge (PHB) includes a memory mapped IO (MMIO) domain descriptor (MDD) and an MMIO Domain Table (MDT) are used to associate MMIO domains with PCI memory VF BAR spaces. One MDD is provided for each unique VF BAR space size per bus segment connecting a single root IO virtualization (SRIOV) device to the PCI host bridge (PHB). The MDT used with the MDD includes having a number of entries limited to a predefined total number of SRIOV VFs to be configured. A VF BAR Stride, which may be further implemented as a VF BAR Stride Capability Structure, is provided to reduce the number of MDDs required to map SRIOV VF BAR spaces. A particular definition of the MDD is provided to reduce the number of MDDs required to at most one per SRIOV bus segment below a PHB.