A number of potential effects of mobile cellular phones on human health have been pinpointed, but the question of whether they affect bone mineralization has rarely been addressed. This study assessed differences in bone mineralization in the right and left hip of healthy male adult volunteers who were either nonusers of mobile phones (n = 24) or users who carried the phone close to the right hip, for at least 1 year (n = 24). Dual-energy x-ray absorptiometry (GE Lunar Prodigy) was performed in dual femur mode for each subject. Right and left hip bone mineral density (BMD) and bone mineral content (BMC) were compared. No difference in mean BMDs and BMCs between groups was found. Nonusers had higher BMC in the right femoral neck (P = 0.0044), a difference absent in mobile phone users (P = 0.028 for the right-left difference in nonusers vs users). Mobile phone users, but not nonusers, had lower BMD at the right trochanter (P = 0.027) and lower BMC at the right trochanter (P = 0.014) and right total hip (P = 0.039). Linear regression showed a correlation between estimated cumulative hours carrying a cell phone on the right hip and differences between right and left trochanter BMD (r = 0.434; P = 0.034). The different asymmetries between right and left hip dual-energy x-ray absorptiometry values in nonusers and mobile phone users suggest that these devices may adversely affect bone mineralization.