The invention relates to a composition A, which is preferably compact and/or anhydrous, comprising at least 20% of red henna powder (Lawsonia inermis, alba) and at least one particular butter, and also an aqueous composition B preferably in the form of a poultice for dyeing keratin fibres, to the process for dyeing keratin fibres by treating the said fibres with the said composition, and to the use of the composition and of a poultice for dyeing keratin fibres. Compositions A and B according to the invention make it possible to dye keratin fibres with strong, chromatic dyeing results that are resistant to washing, perspiration, sebum and light, and that are moreover long-lasting, without impairing the said fibres. Furthermore, the use of compositions A and B does not give off any raw material dust (dust-free). These compositions are easy to use, in total safety and with no risk of staining. In addition, composition A and the dyeing active agent remain stable on storage. The treated keratin fibres have a very pleasant cosmetic aspect, their integrity is respected.
