The paper deals with an assessment of spruce decline using satellite imagery from SPOT, LANDSAT and ASTER. Their spatial resolution from 10 m to 30 m enables mapping at scale of 1 : 25 000 which is required for operational forestry. Regarding the radiometric properties, damage is better distinguishable if middle infrared band is disposable (fig. 1). Almost all area of present spruce occurrence was covered by images and classified. Two-phase regression sampling method was applied to analyse the relationship between spectral signatures derived from satellite data and defoliation. The empirical material consisted of 35 spruce stands where defoliation of trees was evaluated. The strong correlation coefficient r = 0.89 was found, however the standard error of the regression line is quite high syx = ± 15.1 %. It means that defoliation predicted per pixel may vary in this range with 68 % confidence probability. The digital classification of the actual images shows that 7.1 % of spruce forest was classified as heavily damaged or dying in 2008. The portion is even higher in small-scale protected areas, where it is 11.4 % (table 1). The output was processed in a form of thematic maps at scale 1 : 25 000 for each forest district (fig. 2). A gradual increase of calamitous areas has been observed. Change analyses was carried out by visual interpretation of satellite image compositions, created by merging two images from the years 1979 – 1990, 1990 – 2002, 2002 – 2007 and 2007 – 2008. The results confirm that spruce is endangered in all area of its occurrence. The Government of the Slovak Republic dealt with worsening situations of spruce forest. The accepted measures are shortly described