Liquid-crystalline medium having a nematic phase characterized in that it comprises one or more compounds of formula Py in which R 1 an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by -C=C-, -CH=CH-, -O-, -S-, - -O-, -O- - in such a way that O 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 or Cl, or H, A 1 on each appearance, independently of one another, Z 1 independently of one another, identically or differently, denotes a single bond, -CH 2 O-, - O-, -CF 2 O-, -CH 2 CH 2 CF 2 O-, -CF 2 CF 2 -, -CH 2 CF2-, -CH 2 CH 2 -, -(CH 2) 4 -, -CH=CH-, -CH=CF-, -CF=CF- or -C=C-, where asymmetrical bridges may be oriented to both sides, L 1, L 2, L 3, L 4 independently H, F or Cl, L 5 H, CH 3 or CH 2 CH 3, preferably H, X F, Cl, -CF 3, -OCF 3, -CN or -SCN, a denotes 0, 1 or 2, preferably 1, b denotes 0, 1 or 2, preferably 1, and where a + b is ≤ 3, and one or more additional compounds of the formula T in which the individual radicals have the following meanings: R 1 and R 2 denote H, F, Cl, Br, -CN, -NCS or straight-chain or branched alkyl having 1 to 12 C atoms, in which, in addition, one or more CH 2 groups, including terminal C atoms, may each be replaced, independently of one another, by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, -O-CO-, in such a way that O 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 or Cl, L 1 H or CH 3, A 0 denotes A 1, independently of one another, denotes phenylene-1,4-diyl, in which, in addition, one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH 3, CHF 2, CH 2 F, OCH 3, OCHF 2 or OCF 3, cyclohexane-1,4-diyl, in which, in addition, one or two non-adjacent CH 2 groups may be replaced, independently of one another, by O and/or S and one or more H atoms may be replaced by F, cyclohexene-1,4-diyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, m in each case, independently of one another, denotes 0, 1 or 2. R 1 an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by -C=C-, -CH=CH-, -O-, -S-, - -O-, -O- - in such a way that O 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 or Cl, or H, A 1 on each appearance, independently of one another, Z 1 independently of one another, identically or differently, denotes a single bond, -CH 2 O-, - O-, -CF 2 O-, -CH 2 CH 2 CF 2 O-, -CF 2 CF 2 -, -CH 2 CF2-, -CH 2 CH 2 -, -(CH 2) 4 -, -CH=CH-, -CH=CF-, -CF=CF- or -C=C-, where asymmetrical bridges may be oriented to both sides, L 1, L 2, L 3, L 4 independently H, F or Cl, L 5 H, CH 3 or CH 2 CH 3, preferably H, X F, Cl, -CF 3, -OCF 3, -CN or -SCN, a denotes 0, 1 or 2, preferably 1, b denotes 0, 1 or 2, preferably 1, and R 1 and R 2 denote H, F, Cl, Br, -CN, -NCS or straight-chain or branched alkyl having 1 to 12 C atoms, in which, in addition, one or more CH 2 groups, including terminal C atoms, may each be replaced, independently of one another, by -CH=CH-, -C≡C-, -O-, -S-, -CO-, -CO-O-, -O-CO-, in such a way that O 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 or Cl, L 1 H or CH 3, A 0 denotes A 1, independently of one another, denotes phenylene-1,4-diyl, in which, in addition, one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH 3, CHF 2, CH 2 F, OCH 3, OCHF 2 or OCF 3, cyclohexane-1,4-diyl, in which, in addition, one or two non-adjacent CH 2 groups may be replaced, independently of one another, by O and/or S and one or more H atoms may be replaced by F, cyclohexene-1,4-diyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, m in each case, independently of one another, denotes 0, 1 or 2.