We present a new system for simultaneous morphological and molecular analysis of thick tissue samples. The system is composed of a computer assisted microscope and a JAVAbased image display, analysis and visualization program that allows acquisition, annotation, meaningful storage, three-dimensional reconstruction and analysis of structures of interest in thick sectioned tissue specimens. We describe the system in detail and illustrate its use by imaging, reconstructing and analyzing two complete tissue blocks which were differently processed and stained. One block was obtained from a ductal carcinoma in situ (DCIS) lumpectomy specimen and stained alternatively with Hematoxilyn and Eosin (H&E), and with a counterstain and fluorescence in situ hybridization (FISH) to the ERB-B2 gene. The second block contained a fully sectioned mammary gland of a mouse, stained for Histology with H&E.We show how the system greatly reduces the amount of interaction required for the acquisition and analysis and is therefore suitable for studies that require morphologically driven, wide scale (e.g. whole gland) analysis of complex tissue samples or cultures.2