Sanitizing hatching eggs may reduce the chances that a broiler flock will become colonized with Salmonella and reduce the numbers of other microorganisms, such as Enterobacteriaceae, that can depress hatchability. An experiment was conducted to determine if a quaternary-biguanide sanitizer applied as foam or spray would reduce Enterobacteriaceae or Salmonella naturally occurring on broiler hatching eggs. The sanitizer was applied to buggies of 5,040 eggs the day before set (one buggy/treatment at each of 2 settings). Treated eggs were compared with untreated controls. Foam application lowered Enterobacteriaceae prevalence at set (0 vs. 18%) and transfer (5 vs. 28%); spraying was effective only when eggs were set (2.5 vs. 11%). At transfer spray, treated and control eggs were 19% Enterobacteriaceae-positive. Five Salmonella-positives were recorded during the study. No indication that the sanitizer was effective in reducing Salmonella prevalence when applied as foam was observed (3/120 vs. 1/120). No Salmonella were recovered from spray-treated eggs. No statistically significant difference for Salmonella prevalence was noted, but with such a low rate of recovery it is difficult to draw a firm conclusion. However, the sanitizer applied as foam was effective at decreasing the prevalence of Enterobacteriaceae (a family of bacteria that includes Salmonella and Escherichia coli), and is present more often and in higher numbers than Salmonella.