This study examined the relationship between psychological mood, stress and oral hygiene behaviour in a group of 51 regular dental attenders. Subjects brought a saliva sample for cortisol radioimmunoassay, completed the Hospital Anxiety and Depression (HAD) Scale, were assessed for plaque and gingivitis, and were then instructed in toothbrushing. 5 weeks later, 47 subjects were given a full repeat examination. There was a slight reduction in plaque and gingivitis scores, but no change in mood as assessed by HAD Scale and salivary cortisol concentration. Mean anxiety scores were associated with gingivitis level, and mean depression scores with plaque. Neither mood nor cortisol were predictors of subsequent change in plaque or gingivitis.