Abstract: An experiment was conducted to find out the importance of various characteristics of mammary system and to study their relationship with milk yield in dairy cows during the period from October to November 2000. By a previously prepared module, 100 dairy cows were selected to collection of data for the various measurements and shapes of udder from the Bangladesh Agricultural University Dairy Farm and adjacent villages of University. The phenotypic correlation coefficients between udder measurements and test milk yield and between all possible combinations of udder measurements were significant (P<0.01), revealed that length, width and depth of udder were related to each other and also to the milk production. A bowl shaped udder with large proportion of secretory tissue with highest milk production was as an assets for a milch cow. It may be concluded that a well conformation of udder is to be considered for selecting dairy cows on milk yield.