Abstract: To establish an efficient breeding system in tall fescue (Festuca arundinacea), molecular markers related to heat and summer tolerances were screened for marker-assisted selection breeding. Initially, 216 single plants from 12 germplasms differing in heat tolerance were used as a basic population to identify their heat stress (40℃/35℃, day/night, 12 h/12 h) tolerance in an artificial climate chamber and their summer stress tolerance in experimental fields in Shanghai. Random amplified polymorphism DNA (RAPD) and inter-simple sequence repeat (ISSR) were assessed with modified bulked-segregant analysis (BSA) to screen for molecular markers among the 800 RAPD and 100 ISSR primers. The correlation between heat and summer tolerance among single plants was quite low with only 3.4% of the determination coefficient; Primer “351” amplified a 750 bp band (351-T750) which was significantly related to heat tolerance, while “138” amplified a 950 bp band related to both heat and summer tolerance. Heat and summer tolerant single plants should be screened under artificial heat and natural summer stresses respectively; Band 351-T750 could be used only for heat tolerant plant selection, while 138-T950 could be used for both heat and/or summer tolerant plant selection.