Lubricating oils are the most used type of lubricant in many commercially used gearboxes. Due to special requirements and environmental conditions, however, the need for drive systems without oil lubrication is increasing, which can be met in certain applications using lubricating greases. Replacing lubricating oil with grease, and the associated change in the properties of the lubricant, leads to new requirements for the design, calculation and tribological description of the respective gearbox. This work deals with the rheological properties of greases, the tribological description of a grease-lubricated contact and the behavior of lubricant distribution within a gearbox. For this purpose, various lubricants are examined using different tribometers and the behavior in a real gearbox is analyzed. In addition to that the results of the experimental analysis are compared to analytical calculation methods to describe the tribological contact. The tribological investigations include film thickness measurements on a modern EHL tribometer as well as viscosity and friction coefficient measurements. For the behavior in real gearboxes, tests are presented for the analysis of grease distribution using fluorescent particles in the lubricant during operation. The results of these investigations are used to demonstrate the potential and take advantage of greases in worm gears by predicting the friction in the grease-lubricated application and designing the gearbox for the resulting demands.