High resolution optical imaging of living tissues, a process known as intravital imaging, has become a powerful tool for understanding biological processes in the most physiologically relevant manner possible. Recent advances have even enabled direct visualization of delicate internal vital organs such as the lung and the heart. Unfortunately however, these protocols involve extremely invasive, terminal surgeries that limit the duration of imaging and allow no more than one imaging session. We present here a minimally invasive surgical protocol for the implantation of a permanent, indwelling, optical imaging window into the chest wall of a mouse to allow high resolution imaging of the lung. The window reseals the thoracic cavity, enabling the mouse to survive the surgery and breathe independently, and makes imaging of the lung tissue over days to weeks possible.