The production and loss of stratospheric OH involve relatively fast reactions that are in near-photochemical equilibrium. In this study, we compare OH measured by our balloon-borne far infrared limb observing spectrometer with that predicted from a simple model that uses water and ozone fields obtained from instruments on the upper atmosphere research satellite. This comparison is made for latitudes near 34 ¿N over a full diurnal cycle for five balloon flights that span a period of over 2 years. The ratio of measurement to the photochemical model at 40 km is 0.95, with an uncertainty of 0.08 (at a 90% confidence level) due to the measurement. Comparison at other altitudes and as a function of the diurnal cycle also shows excellent agreement. ¿ American Geophysical Union 1996