The present vector studies show that the biting midge, Culicoides furens, serves as an intermediate host for Mansonella ozzardi in Haiti. A total of 3,430 C. furens were collected as they engorged on infected individuals. Under the maintenance conditions described herein, the microfilaria required 9 days to reach the infective stage. Approximately 43% of the midges survived, and from these 1,128 infective stage larvae were collected. This represents an overall infection rate of 0.76 larva per midge. Typically, there was a directly proportional relationship between the infection rate in midges and the level of microfilaremia in the individual upon whom the C. furens fed. Also, the vector efficiency of C. furens collected from saltwater or freshwater breeding habitats was comparable.