The present study was conducted to examine the effect of hatching egg sanitizers on the microbial load and hatchability of broiler breeder hatching eggs. For this purpose, five commercial egg sani- tizers were used, A (H₂O₂), B (quaternary ammo- nium compound), C (H₂O₂& peracetic acid), D (gluatraldehyde & quaternary ammonium com- pound) and E (formalin). A total of 1225 hatching eggs were allotted into 7 groups each of 165 eggs. The first four groups were treated with a mixture of (H₂O₂+ quaternary ammonium compound (QA)) in a low & high concentration, both as a dip and as a spray treatment. The fifth and the sixth groups were treated with C and D respectively, while the last group was fumigated with formalin. Results showed that complete reduction of the total bacterial count from egg shell was obtained when eggs were treated with (H₂O₂+ QA) in high concentration and formalin fumigation after 24 hours of application. For the total fungal count results, none of the used disinfectants reduced it after 24 hours except formalin, but the high concentration of (H₂O₂+ QA dipping) and peracetic acid could produce 85.7% reduction. Regarding hatching results, the highest hatchability of fertile eggs (95.2%) was obtained when eggs were treated with peracetic acid or with the mixture of H₂O₂+ QA (in a low concentration as a dip). While the least percentage of hatchability of fertile eggs and the highest total embryonic deaths (91.7&7.8%) were obtained when eggs were treated with the high concentration of H₂O₂+ QA, Formalin fumigated eggs recorded 93.7% hatchability of fertile eggs and the highest percentage of culls 4.9%. So, the proper use of the disinfectant in chicken hatcheries is essential and the evaluation of alternative disinfectant to formalin should not only based on its antimicrobial activity but also on its ability to maintain the hatching potential as well as its safety for hatchery employees.