The lying down behaviour of 48 dairy heifers was studied while they were tethered for different lengths of time. Heifers were tethered in stalls with concrete flooring either for the entire experimental period (which lasted 24 days), or the last 10 days or the last 3 days of the experiment. In the control treatment, heifers were housed straw-bedded pens. Behavioural observations were recorded for 24 hours at the end of the experiment. Heifers that were tethered for 3 days had longer latencies to lie down, they lied down less and took longer to lie down. The number of lying down interruptions was higher for heifers tethered for 3 and 10 days compared to the control treatment. The heifers tethered for 24 days were in between (did not differ from the control or 3 and 10 day treatments). The results indicate that initial tethering causes the most problems in lying down behaviour for heifers. The results do not indicate that complete adaptation occurs (at least not during the 24 days of this study).