Mastitis constitutes the main health issue in dairy cows farms, because it is widespread and leads to high economic loses. Copper and especially zinc have shown to increase cows’ resistance to mammary infections. However, the levels of these minerals in rations varies greatly, and then, there is a gap of knowledge with regard to the relationship between the levels of trace minerals in the diets used to feed dairy cows, and the incidence of mammary diseases. To contribute in this sense, we carried out this study, with the objective to evaluate the relationship between the level of zinc and copper and udder health parameters. For this purpose, 55 farms representative of the Spanish production systems were selected. The statistical procedure followed was based on bivariate correlation analysis and ANOVA. Results showed that negative and significant correlations existed between the level of dietary copper and the following indicators: Somatic Cell Counts (R2 = 0.138, P = 0.008) and monthly rate of clinical mastitis (R2 = 0.093, P = 0.031). However, no significant correlations were found with the rest of indicators: mastitis prevalence, new infections rate, curation rate in lactation, curation rate in the dry period, and new infections rate at calving. Regarding zinc levels, a significant correlation was found with the curation rate in the dry period (R² = 0.136, P = 0.008). As it can be observed, weak and few correlations were found. Surprisingly and contrary to most of the scientific knowledge, the effect of zinc had a low impact on udder health and resistance. These results could be showing interactions between minerals levels and other dietary compounds. Also, as levels of zinc were above the recommendations, a low response to increasing zinc levels was found. On the contrary, as not all diets were satisfying animals’ needs for copper, higher responses to the level of this mineral were found. Further research is needed to have a deeper knowledge about both minerals interactions and the levels of minerals above which host’s resistance do not increase significantly.