The magnetic equivalent of the contingent negative variation (CMV) and visual evoked magnetic fields (VEF) in anticipation of pictures of opposite-sex nude, same-sex nude, and neutral photographs has been recorded with whole-head MEG in 12 males and 12 females. Subjective ratings of valence indicated a strong gender effect. While females rated both male and female nudes as neutral, males rated male nudes similar to neutrals but female nudes received higher scores of pleasantness. Gender differences were also found for ratings of picture-induced arousal. While females rated male and female nudes as equally arousing, males attributed more arousal to opposite-sex nudes. The CMV instead revealed, for both male and female participants, higher amplitudes for opposite-sex nudes. VEF in response to nudes revealed two components with mean latencies of 126 and 203 ms. The amplitude of the first component was stronger in males than in females, and only in males the magnetic activity was increased in response to male and female nudes compared to neutral pictures. For the second component the mean magnetic activity was higher in response to nudes than to neutral contents for both male and female participants. The results are discussed in terms of an evolutionary view of sexual selection, which predicts a greater response in male subjects to stimuli relevant for mate choice.