Liquid crystal medium, characterised in that it comprises one or more compounds of formula M wherein R M denotes straight chain or branched alkyl or alkenyl having up to 7 C atoms, and one or more compounds of formula IA wherein r denotes 0 or 1, and, independently of one another, denote or wherein Y denotes S or O, and wherein in the 1,4-phenylene groups, one C-H group or a plurality of CH groups, may be replaced by N, and L° on each occurrence, independently of one another, denotes H, Br, Cl, F, -CN, -NCS, -SCN, SF 5, C 1 -C 10 alkyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, R 03, R 04 each, independently of one another, denote a halogenated or unsubstituted alkyl 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-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -C O-, -OC -, -C -, -O- or -S- in such a way that O or S atoms are not linked directly to one another and, optionally, independently of one another, R 03 may also denote ethynyl (i.e. -C≡CH) and R 04 may also denote H, and R 05 and R 06 each, independently of one another, denote a halogenated or unsubstituted alkyl radical having 1 to 6 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-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -C O-, -OC -, -C -, -O- or -S- in such a way that O or S atoms are not linked directly to one another, and one or more compounds of formula VI in which L 61 denotes R 61 and, in the case where Z 61 and/or Z 62 denote trans -CH=CH- or trans -CF=CF-, alternatively also denotes X 61, L 62 denotes R 62 and, in the case where Z 61 and/or Z 62 denote trans- CH=CH - or trans -CF=CF-, alternatively also denotes X 62, R 61 and R 62, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, X 61 and X 62, independently of one another, denote F or Cl, -CN, -NCS, -SF 5, fluorinated alkyl or alkoxy having 1 to 7 C atoms or fluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C atoms, or -NCS, one of Z 61 and Z 62 denotes trans -CH=CH-, trans -CF=CF- or -C≡C- and the other, independently thereof, denotes trans -CH=CH-, trans -CF=CF- or a single bond, and to independently of one another, denote or R M denotes straight chain or branched alkyl or alkenyl having up to 7 C atoms, r denotes 0 or 1, and, independently of one another, denote or wherein Y denotes S or O, and wherein in the 1,4-phenylene groups, one C-H group or a plurality of CH groups, may be replaced by N, and L° on each occurrence, independently of one another, denotes H, Br, Cl, F, -CN, -NCS, -SCN, SF 5, C 1 -C 10 alkyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, Y denotes S or O, and wherein in the 1,4-phenylene groups, one C-H group or a plurality of CH groups, may be replaced by N, and L° on each occurrence, independently of one another, denotes H, Br, Cl, F, -CN, -NCS, -SCN, SF 5, C 1 -C 10 alkyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, R 03, R 04 each, independently of one another, denote a halogenated or unsubstituted alkyl 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-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -C O-, -OC -, -C -, -O- or -S- in such a way that O or S atoms are not linked directly to one another and, optionally, independently of one another, R 03 may also denote ethynyl (i.e. -C≡CH) and R 04 may also denote H, and R 05 and R 06 each, independently of one another, denote a halogenated or unsubstituted alkyl radical having 1 to 6 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-, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -C O-, -OC -, -C -, -O- or -S- in such a way that O or S atoms are not linked directly to one another, L 61 denotes R 61 and, in the case where Z 61 and/or Z 62 denote trans -CH=CH- or trans -CF=CF-, alternatively also denotes X 61, L 62 denotes R 62 and, in the case where Z 61 and/or Z 62 denote trans- CH=CH - or trans -CF=CF-, alternatively also denotes X 62, R 61 and R 62, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, X 61 and X 62, independently of one another, denote F or Cl, -CN, -NCS, -SF 5, fluorinated alkyl or alkoxy having 1 to 7 C atoms or fluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C atoms, or -NCS, one of Z 61 and Z 62 denotes trans -CH=CH-, trans -CF=CF- or -C≡C- and the other, independently thereof, denotes trans -CH=CH-, trans -CF=CF- or a single bond, and to independently of one another, denote or