Liquid-crystalline medium, characterised in that it comprises one or more compounds of the formula I, in which R 0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A 1 denotes a) a 1,4-cyclohexylene radical or 1,4-cyclohexenylene radical, in which, in addition, one or more CH 2 groups in these radicals may each be replaced by -O- or -S-, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, c) a radical from the group piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl or fluorene2,7-diyl, where the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, Z 1 denotes a single bond, -CH 2 CH 2 -, -CH=CH-, -CH 2 O-, -OCH 2 -, -C≡C-, -CH 2 CF 2 -, -CHFCHF-, -CF 2 CH 2 -, -CH 2 CHF-, -CHFCH 2 -, -C 2 F 4 -, -COO-, -OCO-, -CF 2 O-, -OCF 2 - or -O-, Q denotes -CH=CH- or -C≡C-, m denotes 0, 1 or 2, and L 1, L 2, L 3 and L 4 each, independently of one another, denote H or F, and additionally comprises one or more compounds of the formula XXV, in which R 0 has the meaning indicated above, X 0 denotes F, Cl, CFs, OCF 3 or OCHF 2, and Y 1 and Y 2 each, independently of one another, denote H or F. R 0 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A 1 denotes a) a 1,4-cyclohexylene radical or 1,4-cyclohexenylene radical, in which, in addition, one or more CH 2 groups in these radicals may each be replaced by -O- or -S-, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, c) a radical from the group piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl or fluorene2,7-diyl, where the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, a) a 1,4-cyclohexylene radical or 1,4-cyclohexenylene radical, in which, in addition, one or more CH 2 groups in these radicals may each be replaced by -O- or -S-, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, c) a radical from the group piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl or fluorene2,7-diyl, Z 1 denotes a single bond, -CH 2 CH 2 -, -CH=CH-, -CH 2 O-, -OCH 2 -, -C≡C-, -CH 2 CF 2 -, -CHFCHF-, -CF 2 CH 2 -, -CH 2 CHF-, -CHFCH 2 -, -C 2 F 4 -, -COO-, -OCO-, -CF 2 O-, -OCF 2 - or -O-, Q denotes -CH=CH- or -C≡C-, m denotes 0, 1 or 2, and L 1, L 2, L 3 and L 4 each, independently of one another, denote H or F, and additionally comprises one or more compounds of the formula XXV, in which R 0 has the meaning indicated above, X 0 denotes F, Cl, CFs, OCF 3 or OCHF 2, and Y 1 and Y 2 each, independently of one another, denote H or F.