Milk production, reproduction and health are the major determinants of profitability in dairy herds. The smooth progress in cow milk yield over the last decades and the positive association found between milk yield and risk of disease outbreak (Heuer et al., 1999; Fleischer et al.,2001; Gallo et al., 2002) increased the interest towards health traits. For providing a contribution to this topic, this study aimed to investigate the incidence of some health disorders in Italian commercial dairy herds and to estimate the effect of these diseases on milk yield and calving interval. Data for this study were from data base of MTP Project, a program aimed to collect functional and health traits of Italian Holstein cows, carried out from 1998 to 2001, in cooperation with some provincial breeder associations (APA) of Veneto. Altogether, records from 6832 lactations relevant to 5497 cows herded in 94 farms were available. In conclusion, health disorders taken into account appeared widespread in dairy herds sampled and frequently affected milk yield at lactation level, whereas their effects on calving interval appeared more occasional.