Benthic macrofaunal biomass data from San Francisco Bay are presented for 43 stations which were sampled in January/February and August 1973. Biomass data for four major groups (Mollusca, Annelida, Athropoda, and a combination of remaining phyla) and for the groups combined are provided with relative rank at each station for each month. Ancillary data collected concurrently with the macrofaunal samples include water column salinity, temperature, and dissolved oxygen.