Investigate the effects of administration of meloxicam and carprofen on the mobility of hens with and without keel fractures.Within each of two experiments a 'blinded' randomised cross over design whereby birds received either the test drug (carprofen or meloxicam) or saline.Two groups of Lohman Brown hens with and without keel bone fractures.The first group (n = 63) was treated with carprofen 25 mg kg(-1) and saline subcutaneously, twice. The second group (n = 40) was treated with meloxicam (5 mg kg(-1) ) and saline subcutaneously. The latency of birds to fly down from perches 50, 100 and 150 cm above the ground was measured after each treatment. Data from experiment 1 and 2 were analysed separately; the effects of drug treatment compared with saline on landing time for birds with and without keel bone fractures were evaluated using MLwiN.In both experiments latency to fly down from perches was longer in hens with keel fractures and there was a significant interaction between perch height and fracture status. For carprofen, at the 50 cm, 100 cm and 150 cm perch heights, birds with fractures took (mean ± SD) 2.5 ± 2.9, 6.8 ± 9.7 and 11.5 ± 13.2 seconds respectively to fly down compared with 1.3 ± 0.5, 2.3 ± 1.2 and 4.2 ± 3.1 seconds for birds without fractures. For meloxicam, at the 50 cm, 100 cm and 150 cm perch heights, birds with fractures took 2.9 ± 2.5, 49.8 ± 85.4 and 100.3 ± 123.6 seconds respectively compared with 0.7 ± 0.5, 2.5 ± 7.1 and 3.0 ± 4.6 seconds to fly down for birds without fractures. There was no significant effect of carprofen or meloxicam treatment.These data provide further confirmation that keel fractures reduce the willingness of birds to move from perches.