Numbers of suspended bacteria in the Newport River estuary, North Carolina, during June to December 1974, were determined by direct counts using acridine orange and epifluorescent illumination on 0.45 μm porosity cellulose acetate filters. Bacteria ranged from 1.95 to 18.4 million cells/ml and were more abundant in the low salinity water (<15‰) of the upper estuary than in the high salinity water (up to 34 ‰) of the lower estuary. The inverse linear distribution of bacteria with salinity in the lower estuary suggests conservative mixing of bacteria. Preliminary observations on the distribution of relative DOM concentrations and on heterotrophic activity also indicate that the bacteria in the lower estuary are relatively inactive compared to the bacteria in the upper estuary and that the upper estuary may be a source of bacteria to the system.