The goal of a breeding programme is to select animals that will be more profitable or efficient than their parents. Two main methods have been developed to allow selection on the breeding objective. The first method is use of selection index that combines individual trait breeding values with economic weights to provide a single measure on which to select animals. The second method measures the breeding objective (e.g. net profit or lifetime profit) directly and provides genetic evaluations for this measure (Visscher and Goddard, 1995). The profitability of a dairy cow is dependent on both outputs (incomes of milk, fat, protein, calving, etc.) and inputs (costs of feed, labour, facilities, etc). Outputs have received considerable attention in breeding objectives for dairy cattle, whilst there has been less consideration of inputs. Feed is a major cost input for dairy producers. Hence, breeding for increasing main gross incomes (milk, fat and protein) and reducing main variable cost (feed) potentially can be of considerable importance. This study was conducted to estimation of genetic variation in income over feed cost (IOFC), as a single trait, and its association with some of other traits in Holstein dairy cows.