Leaves of three ivy (Hedera helixL.) varieties, one with green leaves and two with variegated leaves, respectively with green centre and white-yellow margin (« Aureo-marginata ») and with white-yellow centre and green margin (« Goldheart »), have been studied by light and electron microscopy. At the same time chlorophyll and carotenoid content was studied. Light microscope observations suggest the hypothesis that the two variegated varieties are chimaeras of periclinal « green over white » type, altough the leaf phenotype is considerably different. The plastid ultrastructure of white-yellow areas of « Aureomarginata » and « Goldheart » are similar. The similarity of pigments between green and white-yellow areas and the normal ultrastructure of all the chloroplasts in young leaves, related to hystological observations, suggest that chloroplast degeneration in « Aureomarginata » is caused by the deficiency of some factor having general importance in cell differentiation and therefore, necessary also for plastid development. On the contrary, in « Goldheart » the data about pigments, hystology and ultrastructure of young leaves suggest that in this case the alterations concern particularly the photosynthetic apparatus. In all the cells of the two variegated varieties a paracrystalline body has been observed, both in normal and in altered plastids; in the green leaves variety the paracrystalline structure has been detected only in plastids of epidermal cells. The significance of this structure has been discussed.