The aim of this study was to determine the effects of dietary sepiolite on performance, egg quality, egg yolk cholesterol content and some blood parameters of laying hens during 22 weeks period. For this purpose a total of 135 Lohmann Brown laying hens, 38 weeks of age, were allocated to one control group and two treatment groups. Sepiolite was used at the level of 0, 0.5 and 1% for the diets of control group and the first and second treatment groups, respectively. Dietary sepiolite supplementation did not significantly affect feed intake, egg production, egg weight and feed conversion ratio. The values of egg breaking strength (p<0.01) and egg shell thickness (p<0.05) were increased, egg yolk cholesterol was decreased (p<0.05) by the usage of 1% sepiolite in the diet. Dietary treatments did not significantly affect egg shape index, egg albumen height, egg albumen index, egg yolk index and egg Haugh unit. Dietary sepiolite at 1% reduced cholesterol and triglyceride in serum (p<0.05) and increased total protein in serum (p<0.01). It was concluded that dietary supplementation of 1% sepiolite was effective feed additive in layer feeding due to the reduction in egg yolk cholesterol and improvement in egg shell quality.