Mixed-species bird flocks are a prevalent characteristic of Andean avian communities. We describe the species composition of mixed-species bird flocks observed in a high mountain zone (3,000 to 3,450 m) of Quindío, central Andes, Colombia. The total number of species observed in mixed-species flocks was 42, and the mean number of species and individuals per flock were 5.1 and 11.5, respectively. Flock species composition was similar along the elevation gradient studied. Our observations suggest that five species (Margarornis squamiger, Iridisornis rufivertex, Conirostrum sitticolor, Mecocerculus stictopterus, and Diglossa cyanea) could be nuclear species in the flocks.