The rocket measurements of Johnson et al. [1952] using solar ultraviolet spectrographs have shown that above 35 km the ozone concentration in the daytime decreases approximately exponentially with altitude and that there is an appreciable Concentration of ozone at altitudes up to 70 km. The ozone concentration near its peak value at about 25 km is not expected to change significantly between day and night because of the absorption of ultraviolet radiation at higher levels in the overlaying atmosphere. At altitudes above about 50 km, however, the ozone concentration at night may be expected to increase significantly above its daytime magnitude because of the absence of the ozone photodissociation reaction, which is an important process at these altitudes during the day. We have developed a new method for determining the high-altitude ozone distribution at night using small geophysical sounding rockets. The principle of the present method is to use the moon as a light source and, with rocket-borne photometers, to measure the atmospheric absorption of lunar ultraviolet radiation in the region of strong ozone absorption between 2400 and 2900 A.