The Unit of Rabbit Science and the Department of Animal Science are two Spanish institutions involved in rabbit genetic improvement since 1976. They develop specialised lines, maternal and paternal, for using in three way crossing schemes. The number of maternal lines are four and they are named, line A, line V, line Prat and line H. The paternal lines are two: Line R and line Caldes. The details of their selection programmes are explained, including the nucleus of selection owned by farmers. These nucleus are considered as crucial in the diffusion and use of the lines in crossbreeding. Finally, non comparative data of the reproductive and growth performance of the lines are given.