The role of primates in seed dispersal is well recognized, except in colobines, which are widely distributed in Asian and African tropical forests. Colobines consume leaves, seeds and fruits, usually unripe. A group of proboscis monkeys (Colobinae, Nasalis larvatus) consisting of an alpha-male, six adult females, and several immatures, was observed from May 2005-2006. A total of 400 fecal samples from focal group members covering 13 months were examined with over 3,500 hr of focal observation data on the group members in a forest along the Menanggul River, Sabah, Malaysia. Intact small seeds were only found in 23 of 71 samples in November 2005, 15 of 38 in December 2005, and 5 of 21 in March 2006. Seeds of Ficus (all < 1.5 mm in length ) were found in all three months and seeds from Antidesma thwaitesianum (all < 3 mm) and Nauclea subdita (all < 2 mm) only in November and December, which was consistent with members of the study group consuming fruits of these species mostly at this time. To our knowledge, these are the first records of seeds in the fecal samples of colobines. Even if colobines pass relatively few seeds intact, their high abundance and biomass could make them quantitatively significant in seed dispersal. The potential role of colobines as seed dispersers should be considered by Colobine researchers.