Research on the cell and molecular biology of proteins involved in membrane traffic often requires determination of the effects of various experimental conditions on the subcellular distributions of those proteins. This is most often accomplished by acquiring fluorescence microscope images and visually comparing these images. While this approach is quite suitable for detecting major changes in distributions, it is not sensitive to small changes and does not permit a quantitative and objective analysis. We therefore describe the application of pattern analysis methods to the comparison of sets of fluorescence microscope images. This approach provides a high throughput and reproducible technique to determine whether image distributions differ within a specified statistical confidence, and is shown to resolve image sets indistinguishable by visual inspection.