In this study, the effect of exposure to an 8 mT, 50 Hz extremely low-frequency electromagnetic field (ELF EMF) on memory consolidation of adult male and female mice was studied. For this purpose male and female mice were randomly distributed among six groups (n = 10 in each group). Using passive avoidance task, despite its natural tendency, mouse learns to stay on a small platform to avoidant electric shock. Immediately after the learning session, laboratory animals in the experimental groups were placed in an 8 mT, 50 Hz sinusoidal EMF for 4 h. The second male and female groups were sham exposed (exposure device off) and the third groups were considered as the controls. Twenty-four hours after the learning session, the animals were placed on small platform again and step-down latency was measured as the memory consolidation index. Significant (p < 0.05) decreases were determined among groups in memory function and results showed that exposure to an 8 mT, 50 Hz EMF for 4 h has devastating effects on memory consolidation in male and female mice.