It is difficult to separate toluidine, chloroaniline and dichloroaniline isomers using the normal liquid stationary phases on a non-alkali-treated support. However, toluidine isomers were completely resolved on caffeine, theobromine, theophylline, xanthine and hypoxanthine, and chloroaniline isomers were effectively separated on picolinic acid, quinolinic acid, isonicotinic acid, orotic acid, 3,5-diaminobenzoic acid, theobromine, xanthine, uracil and a mixed stationary phase of melamine and barbituric acid. Further, six dichloroaniline isomers were also effectively resolved on nicotinic acid, isonicotinic acid, picolinic acid, creatine, hydroxy-L-proline, caffeine, hydantion and mixed stationary phases consisting of nicotinamide and p-aminobenzoic acid and of silicone KF-54 and sodium hydroxide. These effective separations were obtained on non-alkali-treated supports.