In this paper, a multi-variable investigation of the effect of the user's hand in terms of SAR in the head has been conducted. The generic mobile phones and phantoms are used in this study. It is found that the SAR can be increased significantly by the presence of the hand. Besides, the SAR is very sensitive to the hand position respect to the phone, and only some positions cause significant increase of SAR. Based on the investigations with the generic models, 2.46 dB increase of SAR has been also found with the realistic phone model and head/hand phantoms. The method used in this paper will be extended in a more comprehensive investigation of the SAR change with realistic scenarios.