Captive birds in collections may be infested with a wide range of parasites. Globally, information on parasitic infections and their health implications in ornithological collections are scarce. In the present study, the prevalence of parasitic infections in an ornithological garden in Tehran was investigated. Samples (n = 109) from various bird species were collected. Direct wet smear, sedimentation, flotation with Sheather's sugar, and modified Ziehl-Neelsen and Giemsa staining were used for parasite screening. Parasites were identified in 57 (52.3%, 95% confidence interval [CI] 42.9–61.7) samples, with protozoans being the most frequently observed organisms, including Cryptosporidium species, Eimeria species, Isospora species, Trichomonas species, and Histomonas species. Helminths were observed in 29 (26.6%, 95% CI 18.3–34.9) of the samples and included strongyles, Capillaria species, and Raillietina species. Ectoparasites were rarely recovered, but 2 species were identified: the poultry shaft louse (Menopon gallinae) and the fowl tick (Argas persicus). Free-ranging birds were significantly (P < 0.001) more likely to have parasites in their feces than caged birds. Fecal parasitic infections were order dependent and more prevalent in the Anseriformes and Galliformes (P < 0.05). The frequency of gastrointestinal parasites was notable in the investigated collection. In open natural bird gardens, such as in the present study, the probable transmission routes and sources of the parasitic infections are most likely via the free-ranging avian species. It is wise to recommend regular screening of the birds in these gardens to improve preventive control measures. Additionally, parasite genotyping should be considered to clarify our understanding of the epidemiology of zoonotic and nonzoonotic parasites.