Benthic foraminifers from 74 core-top sediment samples collected primarily from the continental shelf of the Gulf of Mexico were analyzed to determine a microfaunal indicator for shelf hypoxia to be used in future paleoenvironmental studies. Principal component analysis (PCA) and cluster analysis (CA) of 93 species recognized factors/clusters that were similar to previous investigations of the benthic foraminifers, except that both analyses also identified PCA6/CA6 in the area where hypoxic conditions have been observed. Three low-oxygen-tolerant species, Pseudononion atlanticum, Epistominella vitrea, and Buliminella morgani have high factor loadings in PCA6. The cumulative percentage of three species is defined as the PEB (PEB, Pseudononion, Epistominella, Buliminella) index. The highest PEB values observed in the 74 surface sediment samples occur in the zone of recognized hypoxia on the Louisiana shelf. Values of the PEB index are also elevated along the southern Texas coastline, suggesting that this area may experience periodic hypoxia as well. ?? 2003 Elsevier Ltd. All rights reserved.