There is provided an electrically and chemically stable liquid crystalline compound which exhibits a significantly large value of De and a high voltage holding ratio. The compound is a phenyldioxane derivative represented by formula (1): ##STR1## wherein R represents a C1-C20 alkyl group; each of n1 and n2 represents 0 or 1; each of Q.sub.1 through Q.sub.6 represents a hydrogen atom, a fluorine atom, or a chlorine atom, provided that Q.sub.3 is a fluorine atom or a chlorine atom when n2 is 0, and that at least one of Q.sub.1 and Q.sub.3 is a fluorine atom or a chlorine atom when n2 is 1; each of Za and Zb represents a single bond, --COO--, or --CF.sub.2 O--; Zc represents a single bond or --CH.sub.2 CH.sub.2 --; Y represents a hydrogen atom, a halogen atom, or a C1-C5 halogenated alkyl group in which one or more non-adjacent methylene groups may be replaced by oxygen atoms or sulfur atoms; and each of the elements that constitute the compound may comprise isotopes of the element. The compound also exhibits excellent compatibility with previously known liquid crystalline compounds, and is advantageously used for low voltage driving of liquid crystal displays for TFTs. There are also provided liquid crystal compositions comprising the compound, as well as liquid crystal display elements constructed of the compositions.