Hen egg white contains numerous molecules of interest for human health, including antimicrobial proteins. Little information is available concerning changes in the antimicrobial activity of egg white during storage; therefore, we analyzed the potential of egg white to inhibit growth of Salmonella enterica serovar Enteritidis following storage at 4, 20, or 37°C for 30 days prior to inoculation. Egg white displayed higher anti-Salmonella activity after a few days of storage at 20 and 37°C. The rate of increase in activity was more rapid and pronounced at the higher temperature. However, egg white stored at 20°C retained higher antimicrobial activity than that of egg white stored at 4 or 37°C, when the entire storage period is taken in consideration. In contrast, storage of egg at 37°C for more than 14 days reduced the bacteriostatic potential of egg white. Statistical analyses revealed a correlation between pH and the antimicrobial activity of egg white. Moreover, diminished antimicrobial activity was associated with degradation of ovalbumin and ovotransferrin, as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. However, the fluctuation in anti-Salmonella activity of egg white could not be related to any variation of trypsin-like, chymotrypsin-like, or gelatinolytic activities that potentially account for degradation of antimicrobial egg white proteins.