Chemis3D is a free Java Applet for the online 3D Visualization of Molecular Models. Small molecules as well as macromolecular structures could be manipulated and rendered in a variety of styles and colors. In addition some useful tools permit the user to label atoms or groups and to measure inter-atomic distances. Chemis3D is a small applet, which is quickly loaded and uses most common chemical file formats (*.xyz, *.mol, *.pdb). Its integration in a Web page is very easy and supports many options.