The aim of this study was to determine the mediating role of resilience in the relationship between attachment styles and treatment adherence in patients with chronic disease. The research design was descriptive-correlational. The statistical population included all patients with diabetes and hypertension in Guilan province in 2020. A sample of 399 people were selected by purposive sampling method. There was a significant direct relationship between adherence to treatment with resilience and secure and avoidant attachment style(p<0.01). However, there was no relationship between adherence to treatment and ambivalent attachment(p>0.05). The fit of the mediator model was improved after deleting the two non-significant paths and it was obtained a good fit by releasing the covariance error between the ambivalent attachment and the secure and avoidant attachment (CFI=1.00, RMSEA=0.086). Bootstrap analysis revealed that resilience mediates the associations between endogenous and exogenous variables. Resilience and attachment pattern are important in patients' adherence to the treatment procedure and it is suggested that skills and strategies for coping with the disease stress and increasing the capacity to adaptive coping to life-threatening conditions be included in the treatment program of patients with chronic diseases.