Endoscopic optical coherence tomography (OCT) allowing high-resolution imaging of internal tissue is attractive for medical imaging. Fibre, fibre bundle or GRIN lens rod acting as endoscopic probe is placed in the sample arm of a Michelson interferometer in current endoscopic OCT systems, this arrangement has to be carefully configured to avoid dispersion and polarization fading. In this study, a common path OCT system with outside path length compensation is presented. The system based on Fizeau configuration requires a Michelson interferometer to compensate the optical path difference between the reference and signal light in the Fizeau sensing interferometer. Experiments of path length compensation and vibration are conducted, and the results demonstrate that this outside compensation method is feasible and the system is immune to the vibration which occurs at the Fizeau sensing interferometer. This OCT imaging approach is very suitable for endoscopic imaging and detailed endoscopic OCT system is also presented. Several samples were imaged to demonstrate the performance of the proposed OCT system.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.