Spraying slightly acidic electrolyzed water (SAEW) has been considered as a potential approach to reduce airborne bacteria in laying-hen houses. In this study, the effects of spraying SAEW on airborne bacterial reduction were investigated in a laying-hen house as compared with using diluted didecyl dimethyl ammonium bromide (DDAB). Averaged air temperature reduced by approximate 1 degrees C and average relative humidity increased by 3% at a stable ventilation rate (about 2.5 m3 hr(-1) per bird) in the laying-hen house 30 min after spraying (120 mL m(-2)). Compared with the control without spraying, the airborne bacterial concentration was reduced by about 0.70 and 0.37 log10 colony-forming units (CFU) m(-3) in the 4 hr after spraying 120 mL m(-2) SAEW (available chlorine concentration [ACC] of 156 mg L(-1)) and diluted DDAB (active compound concentration of 167 mg L(-1)), respectively. Compared with spraying diluted DDAB, spraying SAEW was determined to be more effective for reducing airborne bacterial in laying-hen houses. The effects of spraying SAEW and diluted DDAB on airborne bacterial reduction in the laying-hen house increased with the increasing available chlorine concentrations for SAEW (156, 206, 262 mg L(-1)) and increasing active compound concentrations for diluted DDAB (167, 333, 500 mg L(-1)), respectively. Spraying SAEW and diluted DDAB with two levels of spraying volumes (120 and 90 mL m(-2)) both showed significant differences on airborne bacterial reduction in the laying-hen house (P < 0.05).