About 200,000 animals of the Karagouniko breed are kept in Thessaly, central Greece. These sheep are distinguished for their high production and endurance to difficult conditions. A genetic improvement programme for the Karagouniko breed has been established in central Greece by the Karditsa Animal Genetic Improvement Centre in collaboration with the local Artificial Insemination Centre and the Extension Services of the Ministry of Agriculture. At the age of 18 months, the semen of 20 performance tested lambs is used to inseminate 4,000 ewes in a nucleus population of 20,000 controlled animals. The best three or four male lambs are selected on the basis of their daughters' performance and are used for planned matings in the controlled population.