The productivity of subterranean clover overseedings under Mediterranean tree canopy cover was studied, in South-Eastern France, for various cultivars and dates of sowing. Annual production was higher under tree canopy cover than without, but great variations were observed from year to year. The effect of tree canopy cover on seasonal production was clear during winter with a strong increase of forage biomass in comparison with without trees overseedings. Tree canopy cover is as determinant as other factors like cultivar of microsite conditions for explaining biomass production of overseeded subterranean clover.