Dairy cows require individual monitoring around the time of calving to identify any calving difficulties or health problems as early as possible. To assist with the monitoring of parturition. it would be beneficial to understand the behaviour of dairy cows that is associated with normal calving. This study systematically quantified the behaviour of cows to identify what changes in behaviour occur during the 24 h before normal calving compared with that quantified during pre-calving observations during late pregnancy. The behaviour of twenty Holstein-Friesian cows was recorded for 24 h prior to the calf being expelled and for a 24-hour control period during late pregnancy. Continuous focal observations from video recordings were used to quantify daily frequencies and durations of behaviours. Comparisons were made between daily totals recorded in the 24 h before calving and during the control period and each observation was also divided into four six-hour periods to help determine the time when changes occurred before calving. Segmented regression lines were also fitted to identify the point when behaviour changed before calving. The frequencies of lying and tail raising showed consistent increases in the final six-hour period before calving and a significant break point in their segmented regressions. Durations of lying, walking, eating and ground-licking, and number of walking bouts, did not show consistent changes at the time of calving. This study has shown that counting tail raises or transitions between standing and lying could potentially be useful predictors of calving within the following six hours. (C) 2011 Elsevier B.V. All rights reserved.