La fille du régiment (The Daughter of the Regiment) is an opéra comique in two acts by Gaetano Donizetti. It was written while the composer was living in Paris, with a French libretto by Jules-Henri Vernoy de Saint-Georges and Jean-François Bayard.

La figlia del reggimento, a slightly different Italian-language version (in translation by Callisto Bassi), was adapted to the tastes of the Italian public.

La fille du régiment was first performed on 11 February 1840 by the Paris Opéra-Comique at the Salle de la Bourse. The opening night was "a barely averted disaster." Apparently the lead tenor was frequently off pitch. The noted French tenor Gilbert Duprez, who was present, later observed in his Souvenirs d'un chanteur: "Donizetti often swore to me how his self-esteem as a composer had suffered in Paris. He was never treated there according to his merits. I myself saw the unsuccess, almost the collapse, of La fille du régiment."

It received a highly negative review from the French critic and composer Hector Berlioz (Journal des Débats, 16 February 1840), who claimed it could not be taken seriously by either the public or its composer, although Berlioz did concede that some of the music, "the little waltz that serves as the entr'acte and the trio dialogué ... lack neither vivacity nor freshness." The source of Berlioz's hostility is revealed later in his review: "What, two major scores for the Opéra, Les martyrs and Le duc d'Albe, two others at the Renaissance, Lucie de Lammermoor and L'ange de Nisida, two at the Opéra-Comique, La fille du régiment and another whose title is still unknown, and yet another for the Théâtre-Italien, will have been written or transcribed in one year by the same composer! M Donizetti seems to treat us like a conquered country; it is a veritable invasion. One can no longer speak of the opera houses of Paris, but only of the opera houses of M Donizetti." The critic and poet Théophile Gautier, who was not a rival composer, had a somewhat different point of view: "M Donizetti is capable of paying with music that is beautiful and worthy for the cordial hospitality which France offers him in all her theaters, subsidized or not."

Despite its bumpy start, the opera soon became hugely popular at the Opéra-Comique. During its first 80 years, it reached its 500th performance at the theatre in 1871 and its 1,000th in 1908.