Abstract 1. The effect of perching experience on use of ground level nest boxes was tested in medium hybrid hens. Twelve out of 14 hens (86%) reared without perches laid their first egg on the floor when isolated with ground level nests. Only 4 out of 19 hens (21%) reared with perches laid on the floor. Medium hybrids with experience of only one level apparently have difficulty even stepping up to another level. 2. The age at which perches should be introduced to minimise floor laying was investigated in a second experiment with medium hybrids. Five groups had perches provided at 4, 8, 12, 16 and 20 weeks respectively. Floor laying in the first group varied between 0 and 10%. The proportion of floor eggs laid by the other groups was between 31 and 100% initially, falling to between 23 and 43% by the end of the experiment. Provision of perches as early as possible is recommended. 3. In a commercial trial, perches were provided in a rearing pen of 2600 broiler grandparents. A control pen of 2130 birds had n...