Aircraft measurements of peroxyacetylnitrate (PAN) were performed during the TROPOZ II meridional campaign. A specially designed automatic PAN analyzer on board the airplane allowed us to obtain 422 PAN measurements. The data set covers a latitude range from 60 ¿N to 60 ¿S and altitudes up to 11 km. PAN was found to be an important reactive nitrogen species with a mixing ratio range of 4 part per trillion (ppt) (percentile 5) - 1060 ppt (percentile 95). PAN mixing ratio showed a high degree of variability in both hemispheres. In the southern hemisphere, the higher troposphere exhibited a mixing ratio generally below 20 ppt. The highest mixing ratios were observed in the boundary layer. In polluted areas, PAN levels, higher than 100 ppt, were measured in the lower layers (0--5 km above sea level). In the northern hemisphere, concentrations of PAN ranged from 100--250 ppt in the lower troposphere to 20--40 ppt above 5 km. As a matter of fact, we have frequently measured high PAN mixing ratio (>200 ppt) over West Africa. Since very few anthropogenic PAN precursors are normally released in this area, these high PAN levels were probably due to bush fires. ¿ American Geophysical Union 1994