This report summarizes the findings of the 17 published studies involving humans who have been experimentally infected with filarial parasites. Over the past 60 years, 45 individuals have been deliberately infected with Wuchereria bancrofti, Brugia malayi, Brugia pahangi, Loa loa, Mansonella perstans, Mansonella ozzardi, and/or Onchocerca volvulus. The findings from these experimental infections of humans have helped define microfilarial survival and periodicity within human hosts, the prepatent period for the causative agents of lymphatic filariasis, etiologic agents for particular clinical syndromes, immunologic and hematologic consequences of filarial infection, and the role of chemotherapeutic agents in the prevention and treatment of filarial infections.