Nowadays there are more and more empirical studies of sexual fantasies. Fewer are researches on sexual dreams. Even less common are the data on the relation between sexual fantasies and sexual dreams. A lot of questions can be brought up. Is there a correlation between the frequency in fantasies and sexual dreams? Is there a concordancy or discrepancy between these two? What would be the differences between the persons whom sexual fantasies and dreams concord from those who don't concord? Finally is there an interaction between fantasies and sexual dreams? Based on our preliminary results, we present our mains hypothesis and few illustrations.