Abstract: The invention relates to a novel process for the preparation of ergothioneine.The process for the chemical synthesis of the different optical forms of ergothioneine essentially comprises steps which consist in preparing or using an N.sub..alpha.,N.sub..alpha. -dimethylated histidine ester salt (optically active if necessary), treating this compound with an alkyl, alkenyl or aryl halogenothionoformate in the presence of a base, protecting the sulfur-containing substituent in the compound obtained, converting this protected compound to a compound of the trimethylammonium type and freeing the desired ergothioneine by saponification or acid hydrolysis, as appropriate.This process affords a better yield and ensures an excellent optical purity.