Introduction: The purpose of this study was to assess the effectiveness of animal therapy in alleviation of anxiety in pre-school children.Method: The study was carried out as a quasi-experimental study with pre-test and post-test design and control group. The study population consisted of 33 anxious 5-7years old children (participated in a welfare anxiety screening plan held by Counseling Center, Tehran-Iran) between 2018 and 2019. The participants took part in the study voluntarily.The subjects were randomly divided into experimental and control groups (10 in each group). The experimental group was exposed to 8 sessions of animal therapy. The research instrument was Spence Preschool Anxiety Scale (Parent Form) and the data were analyzed on SPSS 21 software.Results: The results showed that animal therapy had a significant effect on general anxiety score after adjusting for post-test scores (f= 32.49 and p= 0.001) with the effect equal to 0.70. In addition, the effect of animal therapy on anxiety of separation (f= 5.63, p= 0.03), generalized anxiety disorder (f= 8.56, p= 0.01), social phobia (f= 14.58, p= 0.002) and specific anxiety (f= 11.63, p= 0.005) was significant with effects equal to 0.30, 0.40, 0.53, and 0.47, respectively. The results also showed that the effect of animal therapy on obsession was not significant (p>0.05).Conclusion: Therefore, it can be concluded that Animal therapy is effective in alleviating anxiety in children.