A hair shampoo comprises a compound of formula:- <FORM:0907188/III/1> in which X1 and X2 may be the same or different and represent oxygen or sulphur; R1, R2, R4 and R5 may be the same or different and represent hydrogen, alkyl alkylol or aliphatic acyl groups; and R3 represents hydrogen or an alkyl group; in admixture with a hair washing agent.  Typical compounds are biuret, thiobiuret, dithiobiuret and their water-soluble and alcohol-soluble mono-and poly-alkyl, alkylol and acyl derivatives expecially those containing not more than two carbon atoms, e.g. 1-methyl-biuret, 1,5-dimethylbiuret, 1-hydroxymethyl-biuret, 1-acetyl-biuret, 1-formyl-5-acetyl-biuret, 1-methyl-thiobiuret, 1-acetyl-thiobiuret, 1-hydroxymethylthiobiuret and 1-methyldithio-biuret.  The shampoo may be liquid, e.g. an aqueous or alcoholic solution, paste or solid and contains in addition to the diamide, conventional soaps or anionic, cationic or non-ionic detergents, for example, alkyl sulphates and phosphates, fatty acyl monoglyceride sulphates, fatty esters of hydroxyalkane sulphonates, alkanolamide sulphates, N-fatty acyl taurides, alkylaryl sulphonates, sulphated ethylene oxide condensates with fatty acids and alcohols and with alkylaryl radicals, and sulphonated oils, all of which may be present as the alkali metal, ammonium, or lower alkanolamine salts; ethylene oxide condensates with fatty acids and alcohols, alkylaryl radicals, polypropylene glycols or alkanolamides, or fatty acyl lysalbinates; N-acyl pyridinium halides or tetralkylammonium halides, or the acetates or sulphates thereof; or N-alkyl-b -aminopropionic acid.  The detergent preferably comprises 5-40% of a liquid or paste composition and 15-98% of a solid or powder composition.  The composition may also include castor or mineral oil, polyhydric alcohol, poly-alkylene glycol ethers, fatty acid esters of alcohols or polyglycol ethers, gum tragacanth, shellac, vitamins, hormones, plant extracts, cholesterol, lanolin, bactericides and buffers.  The preparation preferably has a pH of 4 to 10.ALSO:A hair preparation comprises a compound of formula <FORM:0907188/VI/1> in which X1 and X2 may be the same or different and represent hydrogen, alkyl, alkylol or aliphatic acyl and R3 represents hydrogen or an alkyl group, and a substantially non-volatile organic material which facilitates grooming of the hair.  Typical compounds are biuret, thiobiuret, dithiobiuret and their water-soluble and alcohol-soluble mono- and poly-alkyl, alkylol and acyl derivatives especially those containing not more than two carbon atoms, e.g. 1-methylbiuret, 1,5-dimethyl-biuret, 1-hydroxymethylbiuret, 1-acetyl-biuret, 1-formyl-5-acetylbiuret, 1-methyl-thiobiuret, 1-acetyl-thiobiuret, 1-hydroxymethylthiobiuret and 1-methyldithiobiuret.  These compounds comprise 0.05 to 10% of the hair preparation.  A hair tonic or dressing may take the form of an aqueous, alcoholic or aqueous alcoholic solution.  Specified organic compounds which facilitates hair grooming are castor oil, mineral oil, glycols, polyhydric alcohols and polymerized alkylene oxides, gums and lacquers such as shellac.  The shampoo may be liquid, paste or solid and contains, in addition to the diamide, conventional soaps or anionic, cationic or non-ionic detergents, comprehensive examples of which are detailed. The preparation preferably has a pH of 4 to 10.  Optional ingredients are vitamins, hormones, plant extracts, cholesterol, lanolin, bactericides and buffers.