Pink snow mould caused by Microdochium nivale is a serious cereal and grass disease in several temperate regions. In this study, resistance to snow mould was evaluated under controlled conditions in nine promising breeding populations and two cultivars of Festulolium, three cultivars of Festuca pratensis, six cultivars and two breeding populations of Lolium perenne and one cultivar of hybrid ryegrass using non-hardened plants. In addition, winter survival was evaluated in field plots inoculated with M. nivale. Under controlled conditions, tetraploid entries of Festulolium had a significantly better resistance to snow mould than diploid entries in three out of four tests. Diploid and tetraploid entries of L. perenne showed similar levels of resistance under controlled conditions. In the field trial, entries of both L. perenne and Festulolium that had been exposed to natural selection in northern Norway (above 65°N) showed good levels of winter survival. In general, under controlled conditions snow mould resistance of Festulolium entries was associated with ploidy level, whereas under field conditions winter survival of L. perenne entries was associated with their degree of northern adaptation. However, resistance to snow mould in non-hardened plants tested under controlled conditions was not correlated with winter survival in the field.