We quantified the guina diet (Leopardus guigna) by analyzing 39 scats collected during summer-autumn 2001 in an Andean mixed Nothofagus-Lophozonia forest, southern Chile. Five small mammal species, three passerine species, lizards of one genus, and insects of two orders were identified in the scats. Small mammals were the most frequently consumed prey (47% of all identified prey individuals) and constituted most of the biomass contributed by all prey (75%). The arboreal/scansorial small mammals Oligoryzomys longicaudatus, Irenomys tarsalis, and Dromiciops gliroides were the most frequently consumed vertebrate prey (14.4, 11.5 and 11.5% of all identified prey individuals; 22.7, 21.5 and 18.2% of biomass contributed by all prey, respectively). The frequency of each small mammal species in the scats was not reflected in its respective capture-frequency as evaluated by live-trapping. O. longicaudatus, I. tarsalis, and D. gliroides were overconsumed' regarding their capture-frequency. Akodon longipilis, the most frequently captured species, was not found in the scats. As a whole, the arboreal/scansorial small mammals were preyed upon by guinas much more than expected given their capture-frequency. Our results suggest that the guina is a predator partially specialized for arboreal/scansorial small mammal species, being able to take alternative prey when available.