Thinning has been proposed as a restoration tool to reduce competition between water-stressed young river red gum trees and increase structural complexity of dense cypress pine regrowth. Yet, little is known about the effects of thinning on mammalian communities. To examine this, we undertook two separate studies: 1. Chronosequence study in cypress pine communities in the Pilliga, NSW, and 2. A Before-After-Control-Impact, large-scale thinning experiment assessing short-term responses in river red gum forests along the Murray River. In both studies, we measured effects of thinning on bats, non-volant mammals, and habitat (total, dead and hollow stem density, and CWD volume). As expected, thinning significantly reduced stem (total and dead) density in both vegetation communities and this was reflected by increased bat activity and diversity, which was maintained for up to 40 years in cypress. Hollow-tree density was not affected by thinning. Bat composition was also affected by thinning in river red gum, with edge species more active in thinned sites. CWD volume increased with thinning in both vegetation communities, but was influenced by type of thinning (commercial vs non-commercial). Non-volant mammal diversity and activity was not affected by thinning in either vegetation community, though composition in river red gum shifted with less activity of common brushtail possums and foxes at thinned sites in relation to controls. Results are consistent with the view that bats respond positively to reduced vegetation density, while non-volant mammal responses were inconsistent and may be related to other habitat features (e.g., ground cover) and predator activity.