A parameterization of the mechanisms believed to be responsible for the quasi bienniel oscillation (QBO) in the zonal winds of the equatorial lower stratosphere has been added to a fully interactive dynamical radiative photochemical two dimensional model of the atmosphere. In addition to a well defined QBO in the zonal winds, temperature and column ozone, the model exhibits a strong QBO signal in many of the other modeled trace gases. Large year to year variations, in some cases up to 70%, are predicted. The importance of taking this prediction into account when measuring and interpreting the distributions of these gases is emphasized. ¿ American Geophysical Union 1990