Novel single-molecule techniques allow the observation of single-molecular motors in real time under physiological conditions. This enables one to gain previously inaccessible information about the mechanics of molecular motors, especially their mechano-chemical coupling. As an example, we discuss the DNA import motor of the bacteriophage phi29 and protein import into chloroplasts. In contrast to these highly developed biological molecular motors, artificial molecular motors are still at an early stage of development. Nevertheless, they already give a wealth of information. Our review focuses on how the investigation of artificial and biological molecular motors can mutually enrich each other.