Liquid-crystalline medium based on a mixture of polar compounds, characterised in that it comprises at least one compound of the formula I, in which R 1 and R 1* in each case, 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 in each case 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, Z 1 denotes -CH 2 O- or -OCH 2 -, a denotes 0, 1 or 2, b denotes 1 or 2, and in each case, independently of one another, denote L 1 and L 2 in each case, independently of one another, denote F, Cl, CF 3, OCF 3 or CHF 2, and in that the medium comprises one or more polymerisable compounds selected from the group of compounds M2, M9 and M16 in which P, P 1 and P 2 denote acrylate, methacrylate, fluoroacrylate, oxetane, vinyloxy or epoxy, Sp, Sp 1 and Sp 2 in each case, independently of one another, denote a spacer group or a single bond, where one or more of the radicals P 1 -Sp 1 - and P 2 -Sp 2 may also denote R aa, where at least one of the radicals P 1 -Sp 1 - and P 2 -Sp 2 is different from R aa, R aa denotes F, Cl, -CN, straight-chain or branched alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may in each case be replaced, independently of one another, by -C(R 00)=C(R 000)-, -C≡C-, -N(R 00)-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, R 00 and R 000 in each case, independently of one another, denote H or alkyl having 1 to 12 C atoms, L denotes P-Sp-, H, OH, CH 2 OH, halogen, SFs, NO 2, a carbon group or hydrocarbon group, r denotes 0, 1, 2, 3 or 4, s denotes 0, 1, 2 or 3, and t denotes 0, 1 or 2, and in that it additionally comprises one or more compounds of the formula IIA and one or more compounds of the formula IIB in which R 2A and R 2B in each case, independently of one another, denote H, an alkyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups in these radicals may be replaced by -O-, -S-, -C=C-, -CF 2 O-, -OCF 2 -, -OC-O- or -O-CO- in such a way that O atoms are not linked directly to one another, L 1-4 in each case, independently of one another, denote F or Cl, Z 2 and Z 2' in each case, independently of one another, denote a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF-, -CH=CHCH 2 O-, p denotes 1 or 2, q denotes 0 or 1, and v denotes 1 to 6. R 1 and R 1* in each case, 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 in each case 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, Z 1 denotes -CH 2 O- or -OCH 2 -, a denotes 0, 1 or 2, b denotes 1 or 2, L 1 and L 2 in each case, independently of one another, denote F, Cl, CF 3, OCF 3 or CHF 2, P, P 1 and P 2 denote acrylate, methacrylate, fluoroacrylate, oxetane, vinyloxy or epoxy, Sp, Sp 1 and Sp 2 in each case, independently of one another, denote a spacer group or a single bond, R aa denotes F, Cl, -CN, straight-chain or branched alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may in each case be replaced, independently of one another, by -C(R 00)=C(R 000)-, -C≡C-, -N(R 00)-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, R 00 and R 000 in each case, independently of one another, denote H or alkyl having 1 to 12 C atoms, L denotes P-Sp-, H, OH, CH 2 OH, halogen, SFs, NO 2, a carbon group or hydrocarbon group, r denotes 0, 1, 2, 3 or 4, s denotes 0, 1, 2 or 3, and t denotes 0, 1 or 2, and R 2A and R 2B in each case, independently of one another, denote H, an alkyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups in these radicals may be replaced by -O-, -S-, -C=C-, -CF 2 O-, -OCF 2 -, -OC-O- or -O-CO- in such a way that O atoms are not linked directly to one another, L 1-4 in each case, independently of one another, denote F or Cl, Z 2 and Z 2' in each case, independently of one another, denote a single bond, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -COO-, -OCO-, -C 2 F 4 -, -CF=CF-, -CH=CHCH 2 O-, p denotes 1 or 2, q denotes 0 or 1, and v denotes 1 to 6.