Summary: Anatomic and functional studies of the living body have revealed that organs have structures in space and fluctuations in time that cannot be characterized by one spatial or temporal scale. Such as lung vasculature or vermis of the cerebellum has a structure in which its small scale appears similar to its large-scale form. Similarly, daily heart rate variability or lung ventilation variability undergoes characteristic changes, which are similar regardless of the time interval over which the observations are made. Similarity extends over many spatial and temporal scales. A key question in interpretation of medical images is often how to quantitate small alterations from the normal variation, because accurate morphologic description of a complex biologic structure is difficult, particularly because the complexity is both geometrical and functional. In addition, the spatial and temporal resolution of the imaging devices as well as our visual ability is poor in order to separate fine organizational and functional properties of the living organs and tissues. Post-processing (such as fractal analysis) of the images might help us to better decode image contents where visual and traditional approaches fail.