The objective of this work was to determine the quantitative prevalence of Anoplocephala sp. in thoroughbred horses raised in São José dos Pinhais, PR using the modified centrifugal-flotation technique. Repeatability values for the eggs per gram (EPG) were evaluated at 28-day intervals. The coproparasitological tests were made in 28 one-year old animals, 25 two-year old animals and 28 mares during the 2007 period of January 31st and June 15th. In the comparison of EPG, all mares presented low values than the foals (P = 0.04). The prevalence results indicated 50, 18 and 40% Anoplocephala sp. in mares, one-year old and two-year old foals, respectively. The EPG repeatability data indicated that both foal generations (2005 and 2006) showed values above 70% and that the mares showed values higher than 40%, revealing an optimal condition which could be incorporated for breeding program purposes.