The paper presents the trends in ambient SO 2 , NO x and O 3 concentrations, SO 4 2 - and NO 3 - concentrations in precipitation and S/SO 4 2 - and N/NO 3 - wet-only atmospheric deposition over the period 1993-2001. The trends are presented for selected rural sites operated by the Czech Hydrometeorological Institute. The results show that the remarkable decrease of SO 2 emissions during the 1990s was followed by a statistically significant downward trend in SO 2 ambient levels, SO 4 2 - concentration in precipitation and S/SO 4 2 - wet-only deposition. S/SO 4 2 - wet-only deposition decreased by ca. 30% while ambient SO 2 concentrations decreased by ca. 80%, in line with total Czech SO 2 emissions over the period 1993-2001. In contrast, the ambient NO x concentrations show a significantly downward trend at only five out of 14 stations, while other stations do not have any trend. N/NO 3 - wet deposition does not show any trend between 1993 and 2001. This corresponds to a less pronounced decrease in NO x emissions. N/NO 3 - wet deposition decreased at some stations by ca. 10% (the trend is not statistically significant), while at some stations it had not decreased at all. Ambient NO x concentrations decreased by approximately 35%, NO x emissions decreased by ca. 30%. The SO 2 limit value of 20μgm - 3 for vegetation protection, though vastly exceeded in the past, has not been exceeded since 1999, while the NO x limit value of 30μgm - 3 for vegetation protection has never been exceeded at the 14 stations analysed. Elevated O 3 concentrations and, consequently, AOT40 limit exceedances were recorded at most of the stations under review.