Estimates of benthic algal primary productivity in a stream measured by14C incorporation and dissolved oxygen change gave similar pattern of productivity over the year. However, estimates from the14C procedure were lower than from the D.O. change procedure. The discrepency is related in part to procedural differences but the data from experiments in which14C uptake and D.O. change were measured simultaneously also indicated the community photosynthetic quotients were higher than those commonly used in productivity work.