Rickettsiae are strictly intracellular bacteria belonging to the Rickettsiaceae family. They are transmitted by various arthropods species, which are either vectors or reservoirs for the bacteria. The specific association between Rickettsieae and the vector are extensively studied, moreover Rickettsieae associated diseases are part of a continuously evolving field. Nevertheless, some rickettsiosis, such as epidemic typhus, have been described since the 16th century. Emerging diseases related to these bacteria are being investigated as well as new species, the implication of which is not always clear in human pathology when they are discovered. Some of these diseases are benign, others may be potentially fatal. Clinicians must therefore be aware of them. These issues are reviewed.