The object was to investigate different observed values of benthal oxygen demand and to determine their relationship to various conditions and circumstances. The study showed little correlation between the concentrations and nature of the benthic organics and the benthal oxygen demand of the deposit. However, there was a correlation between the benthic macro-invertebrate population (tubificid worms) and the benthal oxygen demand, which is also supported by some conclusions reached by other investigators. Although the mechanism of this demand is not clear, it seems that it is far larger than that which would be due solely to the respiration of the organisms. The high oxygen demand associated with the worm populations indicates why the present investigation and other researchers have failed to correlate benthal demand with the chemical composition of the deposits. If, as it appears, the influence of the worms raises the demand to a level up to six times the demand without the worms, the relatively small difference in the demands caused by organic contents would not be obvious.