Herpes simplex virus-1 (HSV-1) is an important human pathogen which in a minority of people causes severe infections. In immunocompetent hosts the infection is self limiting. However, a small minority of people have frequent attacks. As NK cells have been implicated in host protection against HSV-1, the aim of this study was to compare NK cell receptor expression in healthy controls and in patients suffering from recurrent HSV-1 reactivations using monoclonal antibodies against NK cell receptors and 3 colour flow cytometry. Eighteen patients were recruited into the study and the results were compared to a control group. The results obtained showed that overall there was no statistical difference between patient and control groups in the expression of the NK cell receptors. There were however, individuals in the patient group (in particular, two members of one family) with significantly reduced level of activating receptors compared to the control group.