Low self esteem in individuals with a psychotic disorder is common and may be related to poorer clinical outcomes. However, there has been little research on devising treatment methods to improve self-esteem either generally or in psychotic patients in particular. The aims of this study were to evaluate the efficacy of a simple cognitive behavioural intervention to improve self esteem in psychotic patients who scored poorly on a self-esteem measure. This pilot study was a randomised control trial with a convenience sample of chronic psychotic inpatients. The cognitive behavioural self-esteem intervention, as an adjunct to treatment as usual (TAU), was compared to TAU alone in patients with psychosis. The individual self-esteem intervention as described by Tarrier (The use of coping strategies and self-regulation in the treatment of psychosis. (2001)) consisted of working with participants to elicit positive self-attributes and then identify specific behavioural examples to provide evidence of this attribute. Emphasis was given to any consequential change in the patient's belief that they had the attribute. The results indicated that this cognitive behavioural treatment for self-esteem used as an adjunct treatment in psychosis, resulted in clinical benefits in terms of increased self-esteem, decreased psychotic symptomatology and improved social functioning. These benefits were largely maintained at 3-month follow-up.