he calculation of pathological association ratio (or relative risk) from two ways contingency tables, allowed to show numerous interrelationships between diseases of 1,205 dairy cows. The analysis concerns the animal during productive life, the lactation (all lactation mixed), a particular one (1st, 2nd, 3rd and more) and the beginning of productive life of cow (three first lactations). The relationships are discussed according to the level of calculation (animal, lactation, or beginning of life). There is some triangular relations: calving trilogy (dystocia-stillbirth-retained placenta), infectious trilogy (foul of the foot-metritis-mastitis), metabolic trilogy (appetite disorders-ketosis-digestive disorders), foot disorders trilogy (lameness-non infectious diseases of foot-foul of the foot). These pathological groups seem to depend from common risk factors (climate-feeding-cowshed hygiene-control of heat-age-culling policy-genetic factors-anatomical or physiological predisposition, animal size...), but, numerous interactions between groups are also shown, leading to consider pathology in farm like a complex entity