Liquid-crystalline medium based on a mixture of polar compounds characterized in that it contains • at least one compound of the formula I, in which R 1 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-, -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, L 1, L 2 and L 3 each, independently of one another, denote H, F, Cl, CF 3, CHF 2 or alkyl with 1-5 carbon atoms, preferably F or alkyl, and m denotes 0, 1, 2, 3, 4, 5 or 6. and • at least one compound selected from the group of compounds of the formulae I-A to I-K-1, in which R 1,R 1* and R 2 each, independently of one another, denote 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-, -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 0 or 1, L 1 and L 2 each, independently of one another, denote H, F, Cl, CF 3 or CHF 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and the compounds of the formula I-C to I-I are employed in the liquid crystalline medium in amounts of 0.5-25 % by weight based on the mixture as a whole. • at least one compound of the formula I, in which R 1 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-, -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, L 1, L 2 and L 3 each, independently of one another, denote H, F, Cl, CF 3, CHF 2 or alkyl with 1-5 carbon atoms, preferably F or alkyl, and m denotes 0, 1, 2, 3, 4, 5 or 6. and R 1 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-, -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, L 1, L 2 and L 3 each, independently of one another, denote H, F, Cl, CF 3, CHF 2 or alkyl with 1-5 carbon atoms, preferably F or alkyl, and m denotes 0, 1, 2, 3, 4, 5 or 6. • at least one compound selected from the group of compounds of the formulae I-A to I-K-1, in which R 1,R 1* and R 2 each, independently of one another, denote 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-, -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 0 or 1, L 1 and L 2 each, independently of one another, denote H, F, Cl, CF 3 or CHF 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and the compounds of the formula I-C to I-I are employed in the liquid crystalline medium in amounts of 0.5-25 % by weight based on the mixture as a whole. R 1,R 1* and R 2 each, independently of one another, denote 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-, -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 0 or 1, L 1 and L 2 each, independently of one another, denote H, F, Cl, CF 3 or CHF 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and