Unicellular organisms, like protists, use gravity as a most reliable environmental parameter for spatial orientation. Thus, gravisensitive protists offer ideal model systems contributing to answering the question whether gravisensation is a common cellular capacity. During the last decades, the gravity related behaviour in several protozoa, mainly ciliates and flagellates, has been investigated. Though the species differ in cell sizes and living conditions, similar mechanisms of graviperception based on mechanosensitive principles seem to exist.