Egyptian clover or berseem (Trifolium alexandrinum L.) is the principle forage crop in Egypt. Unfortunately, the uncertified and uncontrolled local seeds are being contaminated with dodder (Cuscuta spp.) seeds, which affecting negatively both productivity and quality of produced forage. Three field experiments were carried out at Sakha Agricultural Research Station Farm, Kafer El-Sheikh Governorate, ARC, Egypt, during three successive winter seasons; 2008/09, 2009/10 and 2010/11, to investigate the performance of 100 berseem genotypes; 96 farmers seed lots and four commercial cultivars for its resistance/tolerance to dodder infestation. Highly significant differences were observed among the 100 genotypes under evaluation as well as the interaction between the sets and genotypes for all cuts and seasonal yield in the 1^st season. The commercial cultivar; Helali (Genotype no.111) has high potential and high-yielding ability in comparison with other cultivars and landraces. It was bred for relatively high ability to rapid re-growth which may be associated with tolerance to biotic and abiotic stresses. In addition to, some landraces retained the least reduction percent of total chlorophyll. In general, the berseem genotypes under investigation manifested highly significant differences at all cuts and seasonal fresh and dry yield as well as chlorophyll content for reduction percent due to dodder infestation.