Background and Purpose: Chewing nails is one of the most common behavioral problems in childhood that can be caused by anxiety and stress. The purpose of the present study was to investigate the effect of art therapy (storytelling, photography and painting) based on cognitive-behavioral therapy in treating a 7-year-old girl who had this disorder.

Method: This study was an experimental single case study by using multiple-baselines. The intervention program was conducted in 10 sessions with a follow-up of six weeks. The instruments used in this study were clinical interview, observation, parenting styles questionnaire (Baumrind, 1991) and Goodenough–Harris draw-a-person test (DAP) (Goodenough- Harris, 1963). The research design was a single-case experimental multi-line method. Chart and drawing analysis were used to analyze the data.

Results: The results of the study showed that the effect of art therapy (storytelling, photography and painting) based on cognitive-behavioral approach on nail-biting is clinically meaningful. (P > 0.05).

Conclusion: The results showed that art therapy (storytelling, photography and painting) based on cognitive-behavioral approach is effective in reducing nail-biting disorders. Also the person after receiving the treatment, in addition to reducing the factors related to nail chewing, also improved in other areas such as interpersonal and social behaviors. Therefore, it is suggested to researchers that an integrated model based on the findings of this research be developed for the treatment of nail biting.