Brain–computer interfaces (BCIs) provide a novel form of human–computer interaction. The purpose of these systems is to aid disabled people by affording them the possibility of communication and environment control. In this study, we present experiments using a P300 based BCI in a fully immersive virtual environment (IVE). P300 BCIs depend on presenting several stimuli to the user. We propose two ways of embedding the stimuli in the virtual environment: one that uses 3D objects as targets, and a second that uses a virtual overlay. Both ways have been shown to work effectively with no significant difference in selection accuracy. The results suggest that P300 BCIs can be used successfully in a 3D environment, and this suggests some novel ways of using BCIs in real world environments.