Antarctic polar stratospheric cloud (PSC) sightings by the orbiting SAM II sensor during September and October sow a pronounced Quasi-Biennial Oscillation (QBO) signal, and October sightings have increased markedly over the past 10 years in years of westerly QBO phase. The QBO in PSC frequency is likely to affect the rate of Antarctic heterogeneous chemical processes and, hence, ozone depletion. Studies of the observed long-term temperature trend results from the ozone decline through its effect on stratospheric heating rates. A more detailed analysis of data from 1986 and 1987 shows that there were more PSCs in 1987 and that they persisted much later into the spring season as compared to 1986. Qualitatively similar behavior was found for the OClO column abundances and 18-km ozone depletion observed at McMurdo Station during these 2 years. These observations suggest that both the intensity and duration of heterogeneous chemical processes are likely greater during colder, QBO-westerly phase years. ¿ American Geophysical Union 1989