All the studies on immunocompetence and resistance to disease will have to be completed by estimation of genetic correlations with economically important traits already under selection. Negative genetic correlations have been reported between some ITs (monocytes, CD11R1 + cells) and average daily gain [16] . However a larger correlation study considering a higher number of ITs and pig performances is needed and is ongoing in our population. In the future, a more sustainable production system may require a compromise with a slight decrease in performance traded off for a gain in animal robustness. More studies are required to better understand the correlations between ITs and production traits and it is not established which levels of ITs would be good predictors for resistance to pathogens if any. In conclusion, our results show that variation in many ITs is under significant genetic control in pigs and these findings may provide insights in other species. Moreover, based on heritability and correlation estimations, some of the ITs that we have studied might be incorporated into selection schemes, provided they are associated with improved global health and do not exhibit strong antagonisms with other economically important traits.