The prevalence of Cryptosporidium and Giardia infections in pigs was investigated by the use of a direct immunofluorescence assay on two Ohio farms with different management systems. Cryptosporidium and Giardia infections were detected only in weanlings on the farm with slotted and wire floors, but in both weanlings and nursing piglets on the farm with porous concrete floors. Giardia infection was also detected in sows on the latter farm. The farm with porous concrete floors had a significantly higher Cryptosporidium infection rate in nursing piglets and Giardia infection rates in weanlings than the farm with slotted and wire floors. Sows were implicated as the source of both Cryptosporidium and Giardia infections for nursing piglets.