Chikungunya virus is a zoonotic, vector-borne pathogen that has been responsible for numerous outbreaks of febrile arthralgia since its discovery in the early 1950s. In the past decade, the virus has re-emerged more frequently, causing massive epidemics that have moved from Africa throughout the Indian Ocean to India and Southeast Asia. A discussion of the virus, its epidemiology, diagnostic criteria, and immunity are presented in this article.