Lamb data of 70-day live weights from the breeding program of the Ile de France breed have been used to perform a Monte-Carlo simulation study. Different matting strategies of the number of females per male used in progeny test have been compared, to optimise the genetic progress of the breed for this trait. For a constant female number, the simulated strategies have been: 5 males mated with 60 females each, 10 males matted with 30 females each, and 20 males with 15 females each. Genetic gain and inbreeding coefficient at the end of the process have been compared for each strategy. Genetic gain at the end of 18 generation simulated have been larger for the strategy of 5 males with 60 females than for the other strategies. However, not significant differences for genetic gain have been found among the three strategies. Considering that 5 males with 60 females has been the strategy with a larger inbreeding gain (8%), in relation to the other strategies (6%), the options that used a large amount of males are more convenient that the strategy with only 5 males.