1. Three lighting treatments were given to laying hens, for which the bright and dim light of 28-h ahemeral light cycles was provided by incandescent (tungsten filament) lamps only or by combinations of tubular fluorescent or compact gas-discharge lamps with incandescent lamps. 2. There were no differences in entrainment (the proportion of eggs laid in 4, 6 or 8 h modal periods) between the three bright:dim treatments. 3/A fourth ahemeral lighting treatment in which the dim lights were extinguished except during a designated work period (09.00 h to 12.00 h daily) was termed bright:dim:dark. 4. Hens given the bright:dim:dark treatment showed an increased entrainment compared with the three bright:dim light treatments. 5. There were no differences (P>0.05) in egg numbers or mean egg weight between all 4 lighting treatments. 6. Birds given the bright:dim:dark treatment tended to have a lower (P>0-05) food intake compared to the three bright:dim treatments.