The aim of the present work was to investigate the effects of the radiofrequency (RF) electromagnetic fields (EMFs) on human resting EEG with a control of some parameters that are known to affect alpha band, such as electrode impedance, salivary cortisol, and caffeine. Eyes-open and eyes-closed resting EEG data were recorded in 26 healthy young subjects under two conditions: sham exposure and real exposure in double-blind, counterbalanced, crossover design. Spectral power of EEG rhythms was calculated for the alpha band (8 -12 Hz). Saliva samples were collected before and after the study. Salivary cortisol and caffeine were assessed by ELISA and HPLC, respectively. The electrode impedance was recorded at the beginning of each run. Compared with the sham session, the exposure session showed a statistically significant (P Ͻ 0.0001) decrease of the alpha band spectral power during closed-eyes condition. This effect persisted in the postexposure session (P Ͻ 0.0001). No significant changes were detected in electrode impedance, salivary cortisol, and caffeine in the sham session compared with the exposure one. These results suggest that GSM-EMFs of a mobile phone affect the alpha band within spectral power of resting human EEG. electroencephalogram; radio frequency; mobile phone; alpha band EMERGING TECHNOLOGIES IN MOBILE telecommunications, such as radio frequency fields (RF) and microwave radiation, are widely used in our modern society. Prominent examples are the wireless Internet network and mobile phone communications, which are particularly widespread. The extensive use of mobile phones (MP) increases the exposure of human beings to radiofrequency electromagnetic fields. During a phone call, given the close proximity of the MP to the user's head, a part of the electromagnetic field (EMF) can be absorbed by the head and the brain (Schönborn et al. 1998). This exposure to EMF has raised questions about possible effects of the EMF of mobile phones on brain activity.Some earlier studies have investigated the effects of EMFs on resting cerebral activity with somewhat mixed results, but more recently, there has been consistent data, indicating the existence of exposure effects on the alpha bands of the resting EEG.Indeed, data reported by some authors showed an increase in EEG power in the alpha frequency band (Cook et al. 2004;Croft et al.