Background: The effects of electromagnetic field (EMF) on reproductive system have been of critical concern for a long time. It has been shown that the EMF can adversely affect testicular cells and tissue and decrease male fertility. The most important determinants of male fertility are sperm development and motility, which are affected by changes in several factors including lipocalin 2 proteins. In the present study, we investigated the effects of exposure to EMF on testis tissue and expression of lipocalin 2 gene. Methods: Male BALB/c mice (8 weeks old) were exposed to 3 mT EMF for 8 weeks, 4 hours/day. Control group (10 mice) did not receive EMF exposure. After the experimental period, the mice were sacrificed, and their testis tissues were examined by using light microscopy after hematoxylin-eosin staining. Additionally, total RNA and proteins were extracted from testis tissue and used to study the lipocalin 2 expression by real time RT-PCR and Western blot analysis. Results: The histological changes observed in the testes of experimental group included increased number of spermatocytes and Leydig cells, and increased thickness of basement membrane compared with the control group. The mRNA and protein studies showed that expression of lipocalin 2 gene was down regulated in testes of the mice exposed to EMF. Conclusion: Our study showed that EMF down regulates the expression of lipocalin 2, a cytoprotective molecule, in testis tissue. This down regulation can be one of the mechanisms that contribute to the decreased fertility observed after exposure to EMF.