Objective        To determine the effect of triangle wave electromagnetic field (EMF) on the peak bone mass in rats.       Methods      Female SD rats (5 weeks old) were randomly divided into 2 groups

control (n=9) and experimental group (n=9). The rats of the latter group were exposed to a triangle wave EMF at a frequency of 50 Hz and an intensity of 0.1 mT for 90 min every day

while those of the control group were under the same conditions as the experimental group except no magnetic field intervention. In 1

2 and 3 months after magnetic treatment

bone mineral density was determined after abdomen anesthesia. All the rats were executed by drawing-out all the blood in their hearts in 3 months after treatment. ELISA was used to measure the serum contents of alkaline phosphatase (BALP)

leptin (LEP) and tartrate resistant acid phosphatase (Tracp-5b). A computer-aided image processing system was employed to analyze the morphology of the femur after Van Gieson staining.       Results       No significant difference was found in bone mineral density between the experimental group and control in 1 and 2 months of magnetic intervention (P0.05). But in 3 months

significant difference was seen (P0.05). Serum biochemical results showed that the serum content of ALP was increased

and those of Tracp-5b and LEP were decreased

with significant difference when compared with the control (P0.05). The distance of the double fluorescence and the average width of bone trabecula were significantly larger in the experimental group than the control (P0.05).       Conclusion       Low frequency triangular wave electromagnetic field improves the peak bone mass in rats.