Head-mounted displays (HMDs) allow users to observe virtual environments (VEs) from an egocentric perspective. In order to present a realistic stereoscopic view, the rendering system has to be adjusted to the characteristics of the HMD, e. g., the display’s field of view (FOV), as well as to characteristics that are unique for each user, in particular her interpupillary distance (IPD). Typically, the user’s IPD is measured, and then applied to the virtual IPD used for rendering, assuming that the HMD’s display units are correctly adjusted in front of the user’s eyes. A discrepancy between the user’s IPD and the virtual IPD may distort the perception of the VE. In this poster we analyze the user’s perception of a VE in a HMD environment, which is displayed stereoscopically with different IPDs. We conducted an experiment to identify virtual IPDs that are identified as natural by subjects for different FOVs. In our experiment, subjects had to adjust the IPD for a rendered virtual replica of our real laboratory until perception of the virtual replica matched perception of the real laboratory. We found that the virtual IPDs subjects estimate as most natural are often not identical to their IPDs, and that the estimations were affected by the FOV of the HMD and the virtual FOV used for rendering.