Atomic force microscopy (AFM) is an emerging microscopic method for biologists which offers the magnification range of both light and electron microscope, but allows imaging under the natural conditions associated with the light microscope. To biologists, AFM offers the prospect of high resolution images of biological material, images of molecules and their interactions even under physiological conditions, and the study of molecular processes in living systems. This text provides a realistic appreciation of the advantages and limitations of the technique, and the present and future potential for improving the understanding of biological systems.