Recent analysis of ozone trends in the upper stratosphere suggest that models overestimate the decrease of ozone in the upper stratosphere over the last decade (WMO, 1992). We have included the reaction OH+ClO→HCl+O2 in a two-dimensional radiative-chemical-transport model and find that this reaction reduces the ClO/HCl ratio to agree better with observations. The calculated trend in the upper stratosphere is lower and agrees well with some observations. The effect of this reaction on the lower stratosphere is small. The reaction OH+ClO→Cl+HO2 is the main sink for OH in regions of elevated ClO and low ozone such as during the Antarctic Spring. ¿ American Geophysical Union 1993