Project Abstract With the advent of fluorescence probes targeting specific cellular and subcellular events, the role of fluorescent imaging in preclinical arena is getting rapidly stronger. Fluorescence probes mainly consist of the active component, which interacts with the target, and the reporting component such as the fluorescent dye. Operating in the near-infrared spectrum in which the tissue absorption is minimum, these probes can be detected in vivo even if they are located deep in mice. In addition, the advent of near infrared fluorescent proteins as powerful reporters for gene expression studies enhanced the importance of the fluorescent whole-body imaging in small animals. Our company currently offers the only gantry-based combined X-ray CT and Fluorescent Tomography (FLT) system available in the market that can provide 3D whole-body fluorescent images of mice along with anatomic X-ray images. Our main objective in this application is to upgrade our scanner using an intensified-CCD (ICCD) camera that will mainly allow our system to provide Bioluminescence Tomography (BLT) capability in addition to the FLT. Utilization of an ICCD camera will also enhance the FLT by improving the sensitivity and image acquisition speed. Bioluminescence imaging enables visualization of the genetically engineered luciferase gene-based reporter construct in living animals. Application of bioluminescence imaging has grown tremendously in the past two decades for many fields including immunology, oncology, virology and neuroscience due to its unprecedented sensitivity and ease of use. Being gantry based, our upgraded system would be able to acquire bioluminescence images from multiple views and reconstruct 3D BLT images, which is not an option in any commercially available instruments at the moment. Capability of acquiring perfectly co-registered X-ray CT, FLT, and BLT images will place this proposed system and our company to the forefront of the optical molecular small animal imaging market.