A study was conducted to (I) determine rumen degradability (in sacco) of dry matter (DM) and neutral detergent fibre (NDF) of the most important grass species grown in Czech Republic, (II) compare grass species (n = 5) according to calculated degradation parameters, and (III) to establish prediction equations for degradation parameters from chemical composition. Forty samples of the most important grass species (Dactylis glomerata, Phleum pratense, Lolium perenne, Festuca arundinacea, hybrid Felina) were harvested in 2004 and 2005 and analyzed for chemical composition, and DM and NDF in sacco degradability. Results from the in sacco method were used to calculate DM and NDF degradation parameters. The highest DM and NDF degradation parameters were found for Lolium perenne. Effective degradability (ED) of DM calculated at a rumen outflow rate (k) of 0.05 h-1 was the best predicted by NDF (R2 = 0.878), and ED of NDF at k = 0.02 h-1 by crude protein (CP) (R2 = 0.653).