With small screen devices, including mobile and tablet based systems, becoming more common, the effective use of available screen space has become a critical skill in the design of user interfaces. Transient interface components are one technique that allows for a more complex interface to be displayed, in the form components that are only visible 'on-demand", without a significant or permanent on-screen footprint. This paper describes a study of transient user interfaces and the users perception of transient interface systems of different types, as applied in visually rich 3D environments. The primary objective of transient components is to free the screen space of unwanted interface controls, allowing space to be allocated to the main content, thus creating a more immersive experience for the user. This research involved a randomized control study looking at how users interacted with 3D worlds containing transient interfaces and in particular whether their experiences were enhanced with transient systems when compared with both permanently displayed and totally invisible interfaces. Results indicated that users did feel an enhanced level of immersion when using transient interfaces, but that the detail of how and when the transient components were displayed presented challenges. Those challenges, particularly in terms of the users sense of control of the interactive systems, play an important role in how effective such transient interfaces are. Overall the study found transient interfaces to be an effective way of providing users more immersion within a rich 3D space, while also offering improved access to interface controls and information