We provide a review of the assemblage structure of demersal fish resources in four South and Southeast Asian countries. Multivariate techniques (classification and ordination analysis) were used to analyze scientific trawl survey data from a collaborative project in the region. Analyses covered major coastal fishing areas in Bangladesh, Indonesia, Malaysia, and the Philippines. This represents the first such assessment of fish assemblages for the region using a standard analysis framework. Results indicate that spatial patterns of demersal assemblages are influenced by depth. However, other environmental factors such as salinity and substrate type also appear important. Critical fisheries management implications of the observed assemblage patterns are discussed, particularly in terms of the existing spatial management zones. Existing management zones are based on distance from shore and were found to be largely inconsistent with the assemblage patterns observed. If management is to be effective it must be structured to take into account the underlying pattern of the fish assemblages.