The invention relates to 3-ureidoisoquinolin-8-yl derivatives of formula I wherein R1 is alkyl, haloalkyl or cyclopropyl； R2 is H, halogen, pyridazin-4-yl, pyrimidin-5-yl or an optionally substituted pyridin-3-yl, pyridin-4-yl or phenyl group； R3 is alkyl, alkynyl, aminoalkyl, carbamoylalkyl, methylcarbamoylalkyl, alkoxy, haloalkoxy, alkynyloxy, (4-hydroxybut-2-yn-1-yl)oxy, (4-aminobut-2-yn-1-yl)oxy, dimethylaminoalkoxy, carbamoylalkoxy, alkylamino, cycloalkyl, cycloalkylalkyl, cycloalkylalkoxy, hydroxyalkyl, hydroxyalkoxy, alkoxyalkyl, alkoxyalkoxy, carboxyalkyl, carboxyalkoxy, alkoxycarbonylalkoxy, aryl, heteroaryl, benzyl, benzyloxy, 2-cyanoethoxy, 2,3-dihydroxypropoxy, 3,4-dihydroxybutoxy, &mdash；CH2Ra, &mdash；CH2CH2Rb, &mdash；(CH2)n&mdash；C(O)O&mdash；Rd, &mdash；(CH2)n&mdash；N(Rc)C(O)O&mdash；Rd, &mdash；O&mdash；(CH2)n&mdash；N(Rc)C(O)O&mdash；Rd, &mdash；(CH2)n&mdash；Re or &mdash；O&mdash；(CH2)n&mdash；Re； Ra is cyano, acetylamino or N,N-dimethylamino； Rb is cyano or carbamoyl； Rc is H or methyl； Rd is alkyl； Re is pyrrolidin-1-yl, piperidin-1-yl, piperidin-3-yl, morpholin-1-yl, 2-oxopyrrolidin-1-yl, 5-oxopyrrolidin-2-yl, 2,5-dioxopyrrolidin-1-yl, 2-oxoimidazolidin-1-yl, 4-(tert-butoxycarbonyl)piperazin-1-yl, 4-(aminomethyl)cyclohexyl or heteroaryl； R4 is H or methyl； and to the salts of such compounds. These compounds are useful for the prevention or the treatment of bacterial infections.L'invention concerne des dérivés de 3-uréidoisoquinoléin-8-yle de formule I, dans laquelle R1 est alkyle, haloalkyle ou cyclopropyle ； R2 est H, halogène, pyridazin-4-yle, pyrimidin-5-yle ou un groupe facultativement substitué de pyridin-3-yle, pyridin-4-yle ou phényle ； R3 est alkyle, alcynyle, aminoalkyle, carbamoylalkyle, méthyl-carbamoylalkyle, alcoxy, haloalcoxy, alcynyloxy, (4-hydroxybut-2-yn-1-yl)oxy, (4-aminobut-2-yn-1-yl)oxy, diméthylaminoalcoxy, carbamoylalcoxy, alkylamino, cycloalkyle, cycloalkylalkyle, cycloalkylalcoxy, hydroxyalkyle, hydroxyalcoxy, alcoxyalkyle, alcoxyal
