Both Cryptosporidium and Giardia are frequently found in the stool of domestic ruminants, especially young animals. Wild ruminants are also host to these protozoa, but the prevalence of these parasites in both free-ranging and captive nondomesticated ruminants needs to be further investigated. Moreover, the role of wild ruminants serving as reservoirs for these zoonotic parasites remains unclear. Therefore, a cross-sectional survey was conducted to estimate the occurrence of Cryptosporidium and Giardia in captive wild ruminants younger than 6 mo and to determine the potential of these animals to serve as reservoirs for these zoonotic parasites. A total of 67 captive wild ruminants belonging to 21 different animal species at the Antwerp Zoo (Belgium), along with 82 American bison (Bison bison) on a commercial breeding farm, were sampled for the detection of Cryptosporidium and Giardia, using a commercial immunofluoresence assay (Merifluor Cryptosporidium/Giardia IFA). The Cryptosporidium prevalence was 7.5% in the Antwerp Zoo animals and 3.7% in the bison from the breeding farm. All but two of the Cryptosporidium-positive animals were younger than 1 mo of age. Molecular characterization by amplification of the 70-kDa heat-shock protein and the 18S ribosomal DNA gene identified Cryptosporidium parvum in four animals of the Antwerp Zoo. The prevalence of Giardia was 8.9% in the Antwerp Zoo animals and 23.2% in the bison calves. Most Giardia-positive animals were older than 1 mo of age. Molecular characterization on the beta-giardin gene and the triose phosphate isomerase gene identified Giardia duodenalis assemblage A in the Antwerp Zoo and both G. duodenalis assemblage A and assemblage E in the bison calves. These findings indicate that both protozoan parasites are prevalent in captive wild ruminants and that these animals can serve as a potential reservoir for zoonotic transmission.