Technical Abstract: A series of experiments was conducted to determine the relative safety of two hatching egg sanitizing chemicals on embryo viability. On each of four consecutive days broiler breeder hatching eggs were gathered and separated into ten groups of 88 eggs, and then sanitized with BioSentry 904 or Bio-Phene at 1, 2, 6, and 12 times the manufacturer"s recommended concentration. Each rack of eggs was sprayed with 8 oz (240 mL) of solution containing ½, 1, 3, and 6 oz/gal concentrations of either chemical, or controls with water or nothing at all. Following treatment eggs were held in a 66ºF egg cooler and on the morning of Day 5 all eggs were set in an incubator operating at 99.5ºF and 55% relative humidity. The only significant depression in hatchability (78.2%) was found with the BioSentry 904 at a concentration of 6 oz/gal, which was 12 times the recommended concentration. Hatchability of all other treatments was not significantly different when compared to the nonsprayed and water sprayed controls (88.7%). The Bio-Phene group showed no significant decrease in viability with increasing concentrations. Hatched chick quality from eggs sprayed with either Bio-Phene or BioSentry 904 from ½ to 6 oz/gal concentration was comparable to the controls that were not sprayed or were sprayed with water.