OBJECTIVE: To investigate whether low-frequency electromagnetic fields (EMFs) have any harmful effects on alveolar bone and whether melatonin (MLT) and Ganoderma lucidum (GL) have protective effects against those harmful effects. STUDY DESIGN: A total of 56 rats were divided into 7 groups and exposed to EMF produced from high voltage for 8 hours/day: groups 3 and 6, EMF+MLT (10 mg/kg/day); groups 1 and 4, just EMF; groups 2 and 5, EMF+GL (20 mg/kg/day); group 7, controls. Half of the groups were sacrificed on day 26 and the rest on day 52. Histopathological and immunohistochemical analyses of the specimens were performed. RESULTS: Bone resorption, osteoblastic activity, bone matrix, and osteocyte formation were found by histopathological analysis to be statistically significant in the EMF, EMF+MLT, and EMF+GL groups as compared to the control group at day 26 (p<0.05). Bone resorption, osteoblastic activity, bone matrix, and osteocyte formation were statistically significant in the EMF and EMF+GL groups on day 52 (p<0.05). In the immunohistochemical analyses there was a statistically significant difference in the expression of osteopontin and osteonectin of the EMF+MLT and EMF+GL groups on days 26 and 52 as compared to the control and EMF groups (p<0.05). There was a statistically significant increase in the EMF+MLT group on day 52 as compared to the other groups. CONCLUSION: Exposure to EMF caused histological changes in the alveolar bone of the rats. The use of MLT and GL in treatment may be protective against these harmful effects. © Science Printers and Publishers, Inc.