Species ofIxodiphagus(Hymenoptera: Encyrtidae) are parasitoid wasps whose immature forms develop inside ixodid and argasid ticks (Acari: Ixodida). Following oviposition by adult female wasps into the idiosoma of ticks, larvae hatch and start feeding on their internal contents, eventually emerging as adult wasps from the body of the dead ticks. Species ofIxodiphagushave been reported as parasitoids of 21 species of ticks distributed across 7 genera. There are at least ten species described in the genus, withIxodiphagus hookeribeing the most studied as an agent for biological control of ticks. Although attempts of tick control by means of this parasitoid largely failed, in a small-scale study 150,000 specimens ofI. hookeriwere released over a 1-year period in a pasture where a small cattle population was kept, resulting in an overall reduction in the number ofAmblyomma variegatumticks per animal. This review discusses current scientific information aboutIxodiphagusspp., focusing on the role of this parasitoid in the control of ticks. The interactions between these wasps and the ticks’ population are also discussed, focusing on the many biological and logistical challenges, with limitations of this control method for reducing tick populations under natural conditions.