The feeding habits of the common thresher shark (Alopias superciliosus) from the Pacific coast of Ecuador were investigated by using frequency of ocurrence, numeric and gravimetric methods. A total of 122 individuals were collected from July to December 2003 and grouped by sex and maturity state (mature vs. inmature). Stomach contents were examined and classified by components to infer trophic relations. A total of 27 prey taxa were observed as part of the diet of Alopias superciliosus. Overall, Larimus argenteus (RII=1497) was the most important in the diet, followed by Merluccius gayi (RII=333), Dosidicus gigas (RII=281) and Benthosema panamense (RII=239). The Levin’s index allowed to define A. superciliosus as an specialist predator that feeds in oceanic waters.