The experiment was conducted on 192 Hy-Line hens at the age of 25 weeks, divided into 3 groups, 64 hens per group. The birds were kept in individual cages. Three diets were prepared: diet 1 contained 450 g/kg maize, diets 2 and 3, 450 g/kg naked oats, with (diet 3) or without (diet 2) 1 g/kg of an enzymatic preparation with β-glucanase activity. Performance was recorded for 14 weeks, in the 5th week 20 eggs were collected from each group and the fatty acid composition of yolk lipids was analysed. The laying rate in the group fed the maize diet was 93%, in both groups fed naked oat diets, 92%, feed consumption did not differ among groups. The level of fatty acids and their ratio in egg yolks depended on the type of grain used. Yolks in groups fed diets with naked oats had more PUFA and a higher n-6/n-3 PUFA ratio than yolks in the group fed the maize diet. The supplementation of the naked oat diet with β-glucanase had no influence on performance or on the fatty acid profile in egg yolks.