Hydrazine derivatives of formula (I) wherein Y signifies CO or SO2; R1 signifies lower alkyl, lower alkenyl, lower cycloalkyl, lower cycloalkyl-lower alkyl, aryl or aryl-lower alkyl; R2 signifies lower alkyl, halo-lower alkyl, aryl-lower alkyl, aryl-lower alkenyl or aryl when Y signifies SO¿2? and signifies lower alkyl, halo-lower alkyl, lower alkoxy, lower alkoxycarbonyl, acyl, lower cycloalkyl, aryl, aryl-lower alkyl, aryl-lower alkoxy or NR?5R6¿ when Y signifies CO; and R3 signifies hydrogen, lower alkyl optionally substituted by cyano, amino, hydroxy, lower alkoxy, lower alkoxycarbonly, heterocyclyl or heterocyclylcarbonyl, lower alkenyl, lower alkynyl, lower cycloalkyl, lower cycloalkyl- lower alkyl, aryl-lower alkyl, aryl-lower alkenyl, aryl or heterocyclyl; or R?2 and R3¿ together form the residue of a 5-, 6- or 7- membered cyclic amide, cyclic imide, cyclic sulphonamide or cyclic urethane group; R4 signifies lower alkyl, hydroxy-lower alkyl, lower alkenyl, lower cycloalkyl, lower cycloalkly-lower alkyl or a grouping of the formula X-aryl, X-heteroaryl or -(CH¿2?)1-2-CH=CR?7R8¿; X signifies a spacer group; R?5 and R6¿ each individually signify hydrogen, lower alkyl or aryl-lower alkyl; and R?7 and R8¿ together represent a lower alkylene group in which one methylene group is optionally replaced by a hetero atom; and their pharmaceutically acceptable salts inhibit not only the release of tumour necrosis factor (TNF-α) and transforming growth factor (TGF-α) from cells, but also keratinocyte proliferation. They are useful as medicaments, especially for the treatment of inflammation, fever, haemorrhage, sepsis, rheumatoid arthritis, osteoarthritis, multiple sclerosis or psoriasis.