o-Aminophenol derivatives of the general formula (I) or physiologically compatible, water-soluble salts thereof, in which X is oxygen, sulfur or N—R4; R1, R2, R3 may be identical or different and, independently of one another, are hydrogen, a halogen atom, a cyano group, a C1-C4-alkoxy group, a C1-C6-alkyl group, a C1-C4-alkyl thioether group, a mercapto group, a nitro group, a trifluoromethane group, a —C(O)H group, a —C(O)CH3 group, a —C(O)CF3 group, an —Si(CH3)3 group, a C1-C4-hydroxyalkyl group or an aminomethyl group; R4 is hydrogen, a C1-C6-alkyl group, a C1-C4-hydroxy-alkyl group, a phenyl group or an acetyl group; and colorants containing said compounds for keratin fibers.