This is the first quantitative analysis of benthos in Philippine waters and was intended to help in clarifying whether trawl fishing harms the benthos communities (bottom fauna) as believed by certain fishermen. This paper analyses the results obtained from 317 benthic samples taken from Manila and San Miguel Bays from 1957-1958. The surveys were necessary to learn more about the benthos biomass and its role in the understanding of the food supply of the commercial fish and shrimp populations. The study showed that although the animal densities of Manila Bay and San Miguel Bay are numerically similar, the latter is much richer as shown by the presence of larger animals. The benthos biomass was found in more or less quantities in areas whether there was trawl fishing, or not.