Bacterial depth profiles were obtained from 45 sediment samples taken from two sites approximately 100 km east of the crest of the Juan de Fuca Ridge and roughly 80 km east of the nearest extensive basement outcrop using the Acridine orange direct count (AODC) technique. At Site 1026 bacteria were present at all depths. Total bacterial numbers followed the same general depth trend found at other previously analyzed Ocean Drilling Program (ODP) sites. Total counts decreased from near-surface concentrations of 1.47X10 (super 8) to 9.93X10 (super 6) cells cm (super -3) by 8 mbsf. Below this depth, bacterial numbers remained approximately constant to the deepest depth of approximately 70 mbsf at 1.07X10 (super 7) cells cm (super -3) . Dividing cells were present in all samples and generally paralleled total cell numbers, averaging 12% of the total population. At Site 1027, significant bacterial cells were present in 29 of the 33 samples. Total bacterial numbers were highest at the near surface (1.67 approximately 10 (super 8) cells cm (super -3) ) but decreased rapidly with depth, reaching 2.16 approximately 10 (super 6) cells cm (super -3) in the deepest sample at 565.10 mbsf. The bacterial profile in the top approximately 300 mbsf followed the same general trend observed at other ODP sites. Between approximately 374 and approximately 509 mbsf, bacterial populations were lower than expected. Dividing cells were present in 21 of the 33 samples analyzed and were highest at the near surface (1.97X10 (super 7) cells cm (super -3) ), where they represented 12% of the total population. Below this, the numbers paralleled the total count. Dividing cells, however, were absent below 429 mbsf. Two depth zones showed consistently elevated bacterial numbers. The first of these ( approximately 166 to approximately 273 mbsf) was associated with an increase in pore-water ammonia and alkalinity; the second ( approximately 527 to approximately 565 mbsf) was associated with the diffusion of sulfate from the underlying bedrock. As organic carbon concentrations are essentially consistent throughout the bottom 300 m of the hole, the stimulation of bacterial populations in this deeper zone depth is probably caused by the sulfate providing a more efficient electron acceptor at depth. This coincided with removal of CH (sub 4) , and, thus, anaerobic methane oxidation, which has previously been associated with deep elevation of bacterial populations at a number of ODP sites. In addition, aspects of the bacterial distributions seemed to indicate the sequential presence of different bacterial temperature group from the near-surface psychrophilic bacteria to the deeper thermophilic populations.