AbstractBackgroundOne of the constrain in proboscis monkey (Nasalis larvatus) conservation is gastrointestinal helminth (GH) infection. Here, we conducted a study to determine the prevalence of GHs in captive proboscis monkeys in Surabaya Zoo, Indonesia.MethodsTwenty fecal samples were collected from three groups (i.e., nursery cage [NC] [n = 1], communal show cage [SC] [n = 8], and free‐ranging colonies [FC] [n = 11]). The fecal samples have been examined through McMaster and sugar floatation techniques.ResultsThe total prevalence of GH infection was 85.00% (17/20). We confirmed infection of Trichuris sp., Ascaris sp., Strongyloides sp., and Hymenolepis nana with Trichuris eggs was dominant. Although the prevalence of infection was high, the number of eggs per gram (epg) was low.ConclusionGH infection in captive proboscis monkeys in Surabaya Zoo, Indonesia, is highly prevalent. These results were useful for future research, control, and prevention of zoonotic potency purposes.