The objective of this study was to investigate the relationship between level of sward height reduction (SHR) and short-term intake of herbage by lactating dairy cows offered swards differing in initial bulk density (BD). Three experiments were carried out in which cows were presented with swards representing different levels of SHR (nominally described as ungrazed, low, moderate and high). Experiments 1 and 2 differed with respect to initial sward BD [ungrazed sward 1á7 vs. 2á5 kg dry matter (DM) m A3 respectively]. Experiment 3 investigated the interaction between BD and SHR.In each experiment, sixteen Holstein/Friesian cows (®tted with excreta collection bags) grazed for a 1-h period in 200-m 2 plots that had been grazed on the previous day to predetermined sward surface heights (SSH) ( levels of SHR). Herbage intake rates were assessed from changes in live weight, with a correction for insensible weight loss (IWL). Biting rates were recorded from visual observation. High levels of SHR were associated with a signi®cant reduction in SSH, herbage mass and leaf fraction, and a signi®cant increase in sward BD, stem and dead fraction, and DM concentration.Herbage intake, expressed either as DM intake per bite or DM intake per hour, declined as level of SHR increased from low to high. The level of SHR generally had no effect on biting rate. Intake rates varied from 1á9 to 4á4 kg DM h A1 , whereas DM intake bite A1 ranged from 0á5 to 1á3 g. Pooled regression analysis identi®ed SSH (P < 0á001; r 2 0á94) as the principal determinant of DM intake bite A1 . The regression equation was not signi®cantly improved by the addition of terms for leaf fraction, BD, or herbage mass. In Experiment 3, a signi®cant interaction between level of SHR and sward BD was observed. It is concluded that the principal factor controlling intake (g DM bite A1 or kg DM h A1 ), as swards are progressively grazed down, is SSH, but at a high level of SHR, sward BD also in¯uences intake bite A1 .