Sixty-five oestruses in 38 cows were confirmed either by using progesterone concentration determined in milk or by conception to a service on the same day. The cows were fed concentrates through variable-time out-of-parlour dispensers and the number of visits made by each cow to the dispensers was automatically recorded daily and a 10-day running mean calculated. A significant increase or decrease in visits was recorded when the number of visits on one day differed from the mean number of visits during the previous 10 days by at least two standard deviations. Ninety-three increases and 40 decreases in visits occurred within +/- 10 days of the 65 confirmed oestruses. There were significantly more (16) than the expected number of increases on the day before oestrus (P less than 0.001) but at no other time. Recording increased visits to out-of-parlour concentrate dispensers may help to identify oestrus in dairy cows.