The aim of this paper is to investigate the behaviour of uncountable groups of cardinality ℵ\documentclass[12pt]{minimal}
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\begin{document}$${\aleph}$$\end{document} in which all proper subgroups of cardinality ℵ\documentclass[12pt]{minimal}
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\begin{document}$${\aleph}$$\end{document} have modular subgroup lattice. It is proved here that the lattice of subgroups of such a group G is modular, provided that G has no infinite simple homomorphic images of cardinality ℵ\documentclass[12pt]{minimal}
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\begin{document}$${\aleph}$$\end{document}. A corresponding result for groups whose proper subgroups of large cardinality are quasihamiltonian is also proved.