Abstract. NO, NOy (total reactive nitrogen oxides), gaseous HNO3 and particulate nitrate (p-NO3-) were measured at Neumayer Station from February 1999 to January 2000. We found a mean NOy mixing ratio of 46±29 pptv, with significantly higher values between February and the end of May (58±35 pptv). Between February and November, the (HNO3+p-NO3-)/NOy ratio was extremely low (around 0.22) and in contrast to NOy the seasonality of p-nitrate and HNO3 showed a distinct maximum in November and December, respectively. Trajectory analyses and radioisotope measurements (7Be, 10Be, 210Pb, and 222Rn) indicated that the upper troposphere or stratosphere was the main source region of the observed NOy with a negligible contribution of ground-level sources at northward continents. Frequent maxima of NOy mixing ratios up to 100 pptv are generally associated with air mass transport from the free troposphere of continental Antarctica, while air masses with the lowest NOy mixing ratios were typically advected from the marine boundary layer. Due to the highly variable (HNO3+p-NO3-)/NOy ratio and different seasonality of (HNO3+p-NO3-) and NOy, nitrate concentrations in firn caused by deposition of HNO3 and p-nitrate are most probably not directly connected with the atmospheric budget of reac-tive nitrogen oxides. Consequently, there is no straightforward way to derive the total reactive nitrogen content of the paleo-atmosphere from ice nitrate records.