This research was carried out to determine the effect of boric acid added to feed and water on egg quality characteristics of different quail varieties (Coturnix coturnix Japonica). In the research, 300 laying quails in yellow, white, gray and black colors were used. Additive groups; 100 mg/kg boric acid added group in feed (Y100), 300 mg/kg added group in feed (Y300), 100mg/L added group in water (S100), 300 mg/L added group in water (S300), and control (None additive). The research lasted 90 days. During the research, egg quality characteristics were evaluated in eggs collected on certain days of the week on a weekly basis. At least 50 eggs were examined for each trait. Egg shell weight and shell ratio were highest in Y100 group (P<0.001). Egg shell thickness increased significantly in all boric acid groups (P<0.001). Egg yolk color was the best found in the control group (P<0.01). While the albumen height, albumen index, and Haugh value decreased in the groups with boric acid added to the water (P<0.001), the egg yolk level (P<0.001) and yolk index value (P<0.05) were higher in these groups. The shell weight and thickness were lower in the gray genotype (P<0.001). Albumen ratio was higher in yellow and white genotypes (P<0.001), and egg yolk ratio was higher in gray and black genotypes (P<0.05). Yellow color was lower in black genotype (P<0.05). Significant interactions between additive groups and genotypes were calculated. As a result, it has been determined that boric acid significantly affects egg characteristics, especially egg shell characteristics, and gray genotype is disadvantageous in terms of shell quality.