In this study, we investigated how rat reproductive cells, testosterone, and the fatty acid composition of the phospholipid fraction of rats' testis cells are affected by extremely low frequency magnetic field (ELFMF). The change in fatty acid composition of the membrane phospholipid fraction can be the mechanism for this effect. We used a total of 26 male Wistar Albino rats, 14 experimental, and 12 controls. The experimental group rats were exposed to a magnetic field (0.8 mT) for 5 weeks, 3 hr per day. The control group rats were kept between inactive coils. After 5 weeks, the testis tissues and sperm cells of all rats were histopathologically investigated and sperm counts determined. Epididymal sperm count did not change compared to the control group (p>.05). Besides this, amorphous head, banana-like head, hammer head, coiled tail, abnormal mid-piece and tail, multiple, and cytoplasmic-droplet type cell numbers did not change in either group (p>.05). However, a statistical difference was found between the control and experimental groups with respect to head with lack of hook and isolated head type sperm (p<.05). In addition, testosterone levels were also found to be altered (p<.05). In the histopathologic investigation of testis tissue, decreased spermatogenesis in some seminiferous tubules, congestion in blood vessels of the interstitium, and increases in interstitial edema and Sertoli cells were observed. Leydig cells were found to be normal in appearance. The fatty acid of the testis cell membrane phospholipids was decreased in the experimental group with respect to the control group.