The aim of this research was to determine the effects of watercress (Nasturtium officinale R.Br.) on egg production, feed consumption, feed conversion ratio, egg quality traits and fatty acids profile in laying hens. A total of 72 laying hens of 47 weeks age were used. The trials were carried out in 1 control and 5 test groups containing 12 layers each. Each group was divided in 3 subgroups of 4 hens each. The rations of the control group and the test groups were designed to contain 16.8% crude protein and 2,700 kcal/kg metabolizable energy. Watercress at amounts of 0.0, 0.5, 1.0, 1.5, 2.0 and 3.0% was added to the rations of the test groups. Egg quality traits were examined biweekly. Fatty acids profiles were analyzed at the end of the experiment. At the end of the trial differences in egg yield, feed conversion ratio, yolk index and Haugh unit were found to be not significant (P > 0.05), while differences in feed consumption, egg weight, breaking strength, shell weight and albumen index were significant (P < 0.05). Differences in yolk colour index were highly significant (P < 0.01). The values in the groups were 4.75, 5.45, 6.02, 6.65, 7.63, and 8.70, respectively. The differences in yolk fatty acids n-3, n-6, and n-6/n-3 were non-significant. © Verlag Eugen Ulmer, Stuttgart.