A genealogical analysis of Crioula horses registered by the Brazilian Association of Crioula Horse Breeders was performed. The state of Rio Grande do Sul is the largest producer of animals with 89.85 percent of registered animals, of which 45.29 percent were males and 54.71 percent females. The inbreeding coefficient was calculated at 0.88 percent and the average relatedness was 0.65 percent in the total population (animals born in Brazil and imported). Inbreeding increased over the generations. An increase was seen in the average genetic conservation index in animals born after the year 1927 (0) until 2010 (8.67 percent). The average generation interval was 10.3 years and the average age of parents when offspring born were 10.5 years, falling in recent years. The effective population size of founders was 95.19 animals, the number of ancestors contributing to this population was 5086 where 56 ancestors explained 50 percent of the genetic diversity of the breed. Inbreeding is under control in the Crioula horse. The increase in registrations reflects the increased interest from farmers in this breed.
