EP--70170 A Tylosin derivs. of formula (I) are new. (R1 is OH, halogen, NR5R6, NX (opt. substd. by an oxo gp., OH, 1-6C alkyl or 1-6C hydroxyalkyl), or imidazolyl, morpholino or piperazino (each opt. substd. by 1-6C alkyl) or O-COCH2R8; R5 is H or 1-6C alkyl opt. substd. by a OH gp.; R6 is H, 1-6C alkyl opt. substd. by a OH gp., aryl, aralkyl, 3-10C cycloalkyl, CO(O)mR7 or CH2R13; m is 0 or 1; R7 is 1-6C alkyl, aryl, aralkyl, furaryl or pyridinyl; R13 is CH2F, CHF2 or CF3; X is (CH2)n; n is 2-15; R8 is NR9R10 or SR11; R9 and R10 are H or 1-6C alkyl; or R9 + R10 form 3-7C alkylene; R11 is furanyl or pyridinyl; R2 is H or 1-6C alkanoyl; R3 is Me or CH2CHO; R4 is H or OH; A is O, (alpha H, beta OH) or (alpha OH, beta H); the wavy line is a single or double bond; and the broken line is a single or double bond or an epoxy-bridged single bond. Provided that (1) when R1 is OH, R3 is Me and R4 is H, or the broken line is an epoxy-bridged single bond; and (2) when R1 is halogen, R3 is Me or the broken line is an epoxy-bridged bond). - (I) are broad-spectrum antibacterials with greater activity then tylosin. Dose is 0.01-1 g administered 1-4 times daily. EPAB- EP--70170 B Tylosin derivs. of formula (I) are new. (R1 is OH, halogen, NR5R6, NX (opt. substd. by an oxo gp., OH, 1-6C alkyl or 1-6C hydroxyalkyl), or imidazolyl, morpholino or piperazino (each opt. substd. by 1-6C alkyl) or O-COCH2R8; R5 is H or 1-6C alkyl opt. substd. by a OH gp.; R6 is H, 1-6C alkyl opt. substd. by a OH gp., aryl, aralkyl, 3-10C cycloalkyl, CO(O)mR7 or CH2R13; m is 0 or 1; R7 is 1-6C alkyl, aryl, aralkyl, furaryl or pyridinyl; R13 is CH2F, CHF2 or CF3; X is (CH2)n; n is 2-15; R8 is NR9R10 or SR11; R9 and R10 are H or 1-6C alkyl; or R9 + R10 form 3-7C alkylene; R11 is furanyl or pyridinyl; R2 is H or 1-6C alkanoyl; R3 is Me or CH2CHO; R4 is H or OH; A is O, (alpha H, beta OH) or (alpha OH, beta H); the wavy line is a single or double bond; and the broken line is a single or double bond or an epoxy-bridged single bond. Provided that (1) when R1 is OH, R3 is Me and R4 is H, or the broken line is an epoxy-bridged single bond; and (2) when R1 is halogen, R3 is Me or the broken line is an epoxy-bridged bond). - (I) are broad-spectrum antibacterials with greater activity then tylosin. Dose is 0.01-1 g administered 1-4 times daily. (177pp) - EP--70170 B A tylosin derivative represented by the general formula (I) wherein R1 represents NR5R6 (wherein R5 represents a hydrogen atom or a C1 to C6 alkyl group which may be substituted by a hydroxyl group and R6 represents a hydrogen atom, a C1 to C6 alkyl group which may be substituted by a hydroxyl group, an aryl group, an aralkyl group, a cycloalkyl group having 3-10 carbonatoms, -CO(O)m-R7 (wherein m represents 0 or 1 and R7 represents a C1- to C6 alkyl group, an aryl group, an aralkyl group, a furanyl group or a pyridyl group), or -CH2-R13 (wherein R13 represents a mono-, di-, or trifluoromethyl group)); gp. (a) (wherein n represents an integer of 2-15) and which may be substituted by an oxo, a hydroxyl group, A C1 to C6 alkyl group, or a hydroxy C1 to C6 alkyl group; or an imidazolyl, morpholino, or piperazino group which may each be substituted by a C1 to C6 alkyl group; R2 represents a hydrogen atom or a C1 to C6 alkanoyl group; R3 represents a methyl or -CH2CHO group; R4 represents a hydrogen atom or a hydroxyl group; A represents O=, (b) or (c); wavy line reprsents a single or double bond; and dotted line represents a single, a double bond, or (d) provided that when R1 is a hydroxyl group, R3 is a methyl group and R4 is hydrogen atom or said dotted line is (d), and that when R1 is halogen atom, R3 is methyl group or dotted line is (d). (151pp) USAB- US4477443 A Tylosin cpds. of formula (I) are new. In the formula, R1 or OH, halo, NR5R6, cyclic C(CH2)n which is opt. substd. or OOCCH2R8. R5 is H, alkyl or hydroxyalkyl, R6 is as for R5, aryl, aralkyl, cycloalkyl, etc. n is 2-15. R8 is NR9R10 in which R9 is R10 are H or alkyl or combine to form 3-7C alkylene gp., or is S-R11 in which R11 is furanyl or pyridyl. R2 is H or alkanoyl R3 is CH3 or CH2CHO. R4 is is H or OH. A is O, H and OH is either configuration. The dotted bond is opt. present. X is O, 2H or is absent such that a second CC bond is formed. When R1 is OH, R3 os CH3 and R4 is H or X is O. When R1 is halo, R3 is CH3 or X is O.