In the past decade, the use of virtual reality for clinical and research applications has become more widespread. However, the diffusion of this approach is still limited by three main issues: poor usability, lack of technical expertise among clinical professionals, and high costs. To address these challenges, we introduce NeuroVR (http://www.neurovr.org--http://www.neurotiv.org), a cost-free virtual reality platform based on open-source software, that allows non-expert users to adapt the content of a pre-designed virtual environment to meet the specific needs of the clinical or experimental setting. Using the NeuroVR Editor, the user can choose the appropriate psychological stimuli/stressors from a database of objects (both 2D and 3D) and videos, and easily place them into the virtual environment. The edited scene can then be visualized in the NeuroVR Player using either immersive or non-immersive displays. Currently, the NeuroVR library includes different virtual scenes (apartment, office, square, supermarket, park, classroom, etc.), covering two of the most studied clinical applications of VR: specific phobias and eating disorders. The NeuroVR Editor is based on Blender (http://www.blender.org), the open source, cross-platform suite of tools for 3D creation, and is available as a completely free resource. An interesting feature of the NeuroVR Editor is the possibility to add new objects to the database. This feature allows the therapist to enhance the patient's feeling of familiarity and intimacy with the virtual scene, i.e., by using photos or movies of objects/people that are part of the patient's daily life, thereby improving the efficacy of the exposure. The NeuroVR platform runs on standard personal computers with Microsoft Windows; the only requirement for the hardware is related to the graphics card, which must support OpenGL.