The study of many biological processes requires the analysis of three-dimensional (3D) structures that change over time. Optical sectioning techniques can provide 3D data from living specimens; however, when 3D data are collected over a period of time, the quantity of Image information produced leads to difficulties in interpretation. A computer-based system is described that permits the analysis and archiving of 3D image data taken over time, The system allows a user to roam through the full range of time points and focal planes in the data set. The user can animate images as an aid to visualization and can append multicolored labels and text notes to identified structures during data analysis, The system provides a valuable tool for the study of embryogenesis and cytoplasmic movements within cells and has considerable potential as an educational tool.