Branching ratios for several atomic oxygen 3p3D transitions have been studied. A value of 0.0004¿20% for the O I (7990A⊕) branching ratio was obtained, which is much smaller than the previously accepted value and in accord with recent calculations and interpretations of the auroral extreme ultraviolet spectra. Measurements of the O I (7002¿) and O I (11,287¿) multiplets give branching ratios of 0.05 and 0.10, whichare in better accord with calculations. As part of this experiment, results of a study of the highly structured O2 photoabsorption cross section in the neighborhood of the multiplets is also reported.