Objective: The aim of our study is to evaluate possible effects of chronic exposure to 900 - 1800 MHz radiation emitted from 2G cell phone and 1900 -2200 MHz from 3G cell phone on the testis of mice and to compare the effects of 2G and 3G radiation on testis at the histological level. Methods: Mice were exposed to 2G and 3G ultra-high frequency radiation, 48 minutes per day for a period of 30 to 180 days. The sham control mice were exposed to similar conditions without 2G or 3G exposure. Animal__ampersandsignrsquo;s weight of 2G and 3G cell phone exposed group were recorded before sacrificing at the end of 30, 60, 90,120,150 and 180 days. Same numbers of control animals were sacrificed on the same period. Blood samples were collected to measure plasma testosterone. Both the testes were dissected and its size, weight and volume were measured. The testes were processed for histomorphometric study. Results: Following chronic exposure of 2G and 3G cell phone radiation in mice, there was significant reduction of animal weight at first, second and fourth month. The mean testis weight and volume of 2G and 3G radiation exposed mice were significantly reduced in the first three months. The comparison between 2G and 3G exposed groups, showed no significant changes in mean body weight, mean testis weight and mean testis volume. The mean density of seminiferous tubule, mean seminiferous tubule diameter, mean number of Sertoli and Leydig cells of 2G and 3G exposed groups had significantly lower value than the control. The following microscopic changes were observed in the 2G and 3G radiation exposed mice testis over control. 1. Wide interstitium 2. Detachment of Sertoli cells and spermatogonia from the basal lamina. 3. Vacuolar degeneration and desquamation of seminiferous epithelium. 4. Peripheral tubules showed reduced thickness of seminiferous epithelium and maturation arrest in the spermatogenesis. 5. Seminiferous tubules scored 7 to 9 using Johnson testicular biopsy score count. The mean total serum testosterone level of first, second, third, fourth and sixth month 2G and 3G exposed mice had significantly lower serum testosterone level than control. However, comparison between 2G and 3G showed no significant difference in the mean serum testosterone level. Conclusion: Chronic exposure to ultra-high frequency radiation emitted from 2G and 3G cell phone could cause microscopic changes in the seminiferous epithelium, reduction of serum testosterone level, reduction in the number of Sertoli cells and Leydig cells.