Abstract: An improved no-base aqueous sodium hydroxide-based hair-straightening composition having a pH between about 12 and about 14 comprises, as an active hair-straightening agent, a mixture of sodium hydroxide and a lesser amount of a hair keratin-disulfide reducing agent having a sulfhydryl functional group available from the sulfur-containing amino acid cysteine, water-soluble homologs of cysteine and certain water-soluble derivatives of cysteine. The composition augments and enhances the hair-straightening benefits of sodium hydroxide yet substantially overcomes negative hair conditioning problems normally associated with the use of sodium hydroxide. Cysteine is particularly preferred as the hair keratin-disulfide reducing agent. Also disclosed is a hair-straightening system and method for straightening hair with the foregoing compositions.