ABSTRACT. Marques B.C. & Borges F.A.[Frequency of Giardia sp. in the feces of dogs in Campo Grande, MS.] Frequência de Giardia sp. em fezes de cães, no município de Campo Grande, MS. Revista Brasileira de Medicina Veterinária, 36(1):21-23, 2014. Faculdade de Medicina Veterinária e Zootecnia, Universidade Federal de Mato Grosso do Sul, Av. Senador Felinto Muller, 2443, Vila Ipiranga, Campo Grande, MS 79070-900, Brasil. E-mail: email@example.com One hundred and fifty fecal samples were analyzed in order to determine the frequency of Giardia. in dogs in Campo Grande, Mato Grosso do Sul and to evaluate the influence of age, origin and consistency of stools. The frequency of Giardia. found in the feces of dogs was 27.33%. The age did not influence parasitism (P> 0.05), with 30.43% of adults infected and 24.69% of young. Dogs from kennels were the most infected (P <0.05), with 45% positivity, followed by dogs at the Center for Zoonosis Control (24%) and dogs from homes (14.28%). Among the dogs with loose stools, 36.76% were carriers of Giardia, 32.53% of those with diarrhea were positive and dogs with formed feces showed 10.42% positivity. This was the first evaluation of the frequency of Giardia. in dogs in central-west Brazil and the value obtained can be considered high, highlighting the need for measures of parasite control and prevention and treatment of infected animals.