This study was conducted to explore the influence of magnetic treated water with different intensities on milk yield and its components in Holstein cows. This study was executed at the cow farm pertaining to the Department of animal Resources, College of Agriculture, University of Baghdadduring the period from 2/11/2010 to21/2/2011. Sixteen Holstein dairy cows (average dailymilk yield 15 kg / cow/ day), aged between3.5to 4.5 years and with an average of initial body weight between410.5 to 505.67 kg. The cows were randomly divided into 4 equal groups according to their milk yield.The first, secondand third groups were drinking a magnetic water with 1000, 2000 and 3000 Gauss respectively, whereas. The fourth group drunk an ordinary water and regarded as control group. The magnetic water – treated groups were superior (P<0.05) in milk yield as compared with control group, from week 6 until the end of the experiment in particular. The average milk yield of the experiment groups during week 6 were 233.28, 220.28, 228.51 and 208.14 kg respectively. In week 14, the averaged milk yield of the three treated groups were 232.4, 223.92, and 232.75 kg respectively in comparison with 189 kg in control group. The difference among groups in milk components (fat, protein, lactose, solid non – fat) were notsignificant. However, significant difference in milk fat in treated groups was observed with comparison to the first and second treated groups.