A group of Callicebus torquatus lugens using a territory of 22.25 ha in eastern Colombia showed a varied diet throughout the annual period of lowest fruit availability. This is a time when the females are usually pregnant. During a 6-month period the study group's diet consisted of 59.4% fruits, 26.9% immature seeds, 6.4% leaves, 3.9% flowers, and 3.4% insects and spiders. At the fruit bottleneck, consumption of seeds and flowers increased, while consumption of leaves and insects showed no particular trend. They ate 62 species of plants: 45 for flesh, 6 for seeds, 2 for flowers, and 13 for foliage. The most important families in terms of species chosen are Moraceae (8 species, or 11 species if Cecropiaceae is included), Myristicaceae (7), Arecaceae (4), Chrysobalanaceae (4), and Euphorbiaceae. The most important families in terms of feeding time are Myristicaceae (25%), Euphorbiaceae (15%), Moraceae (14%), and Arecaceae (9%). Of 440 marked feeding trees in the territory of the group, 41.1% are represented by Sandwithia heterocalyx (Euphorbiaceae). This species is the most important food in the diet and has the highest density of all food trees in the home range. It followed by Heterostemon conjugates (Caesalpiniaceae) (10%), Iryanthera ulei (Myristicaceae) (6.1%), Anaxagorea brachycarpa (Annonaceae) (5.9%), and Iryanthera crassifolia (Myristicaceae) (3.4%). The remaining 33.5% of the marked trees are represented by the other 57 species. In terms of time spent feeding, the important trees in the diet include Sandwithia heterocalyx (13.9%), Virola melinonii (10%), Iryanthera ulei (8.35%), Oenocarpus bataua (7.06%), and Heterostemon conjugates (6.53%). We suggest that Callicebus torquatus should be described as a frugivore–granivore; they share with the Pitheciin an immature seed-eating adaptation.