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Mistletoes are worldwide occurring evergreen parasites, growing on branches of many trees in temperate and semi-arid regions. They are obligate parasites as they cannot fully assume their own nutrition. Studies carried out on whole plants have shown that they are capable of photosynthesis, though at low rates. To investigate the efficiency of the photosynthetic apparatus, chloroplasts were isolated from the green leaves of two mistletoes originating from temperate (Viscum album) and tropical (Tapinanthus dodoneifolius) areas. Compared to free-living higher plants, mistletoe chloroplasts exhibit low levels of chlorophyll and polar lipids whereas their protein content is less reduced. No significant changes were observed in polar lipid composition. However, in T. dodoneifolius chloroplasts, the proportion of phospholipids is increased. For both mistletoes, polar lipids, mainly phospholipids. display a slight decrease in the degree of unsaturation of fatty acids and contain a large proportion of oleic acid. Mistletoe chloroplasts also show large deficiencies in photosystem activities, particularly those from T. dodoneifolius, correlated with low amounts of chlorophyll-protein complexes. These results are discussed in relation to parasitism and drought adaptation.