To examine the effect of hay on behaviour of caged rabbits, Oryctolagus cuniculus, a study was carried out on 86 rabbits, kept in wire cages with no access to hay in one period and with access to hay in a second period. As the study was part of a larger experiment analysing the rabbits’ behaviour in two different cage systems, the rabbits were equally distributed across two systems: a system with conventional barren wire cages, and an enriched system with boxes and raised height at the back of the wire cages. The rabbits’ behaviour was recorded using direct scan sampling during the day and continuous registration based on video recording at night. When hay was available, the rabbits in both cage systems performed significantly less bar gnawing and excessive grooming. This applied especially to the rabbits kept in the conventional cage system which also showed a distinct decrease in their frequency of changing between different behaviours. This suggests that rabbits kept in cages where hay is available are less stressed than those kept in cages where it is not. Enrichment with hay should, therefore, be considered in attempts to improve the welfare of caged rabbits.