Background: The aim of this study is to determine the effectiveness of positive psychology on anxiety, perceived stress and adherence to treatment in patients with asthma.

Method: The present study is a quasi-experimental design with a two-group pretest posttest design. The statistical population of the present study includes all patients with asthma who referred to Milad Hospital in Tehran in 2019. In order to form two groups using purposive sampling method (considering the entry and exit criteria), first 30 people were selected, and then 15 people were put in the experimental group and 15 people in the control group randomly. The research instruments included Beck Anxiety Inventory (1989), Cohen’s Perceived Stress Scale Questionnaire (1981) and Maurice et al.'s Treatment Adherence Scale (2010). The research data was analyzed using covariance analysis test.

Result: The results showed that positive psychology in the experimental group members had a significant effect on the components of anxiety, perceived stress and adherence to treatment in patients with asthma compared to the control group (p <0.05).

Conclusion: the effectiveness of the positive method on the components of anxiety and Adherence to treatment was significant over time (p> 0.05).