Agile gibbon (Hylobates agilis F. Cuvier 1821) and siamang (Symphalangus syndactylus Raffles 1821) are Indonesian endemic species. Aim of the study to determine the existence and the type of parasitic worms that infected agile gibbon and siamang at Serulingmas Zoological Garden, Banjarnegara. From Juli 2009 to February 2010, feces from three heads of agile gibbon and three heads of siamang was collected each week. All of samples were examined with quantitative and qualitative examination. Identification is achieved by the use of faecal cultures. The result showed that parasitic worms of agile gibbon were Trichostrongylus spp. and Strongyloides spp. and parasitic worms of siamang were Trichuris spp., Trichostrongylus spp., Strongyloides spp., and Cooperia spp. The result of quantitative examination showed that degree of infection by parasitic worms in agile gibbon and siamang belonging to low infection.