Two significant figures of merit for optical coherence tomography (OCT) systems are the axial and transverse resolutions. Transverse resolution has been defined using the Rayleigh Criterion or from Gaussian beam optics. The axial resolution is generally defined in terms of the coherence length of a Gaussian shaped source. Whilst these definitions provide a useful mathematical reference they are somewhat abstracted from the three dimensional resolution that is encountered under practical imaging conditions. Therefore, we have developed a three-dimensional resolution target and measurement methodology that can be used to calibrate the three-dimensional resolution of OCT systems.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.