Background: Anxiety and non-compliance with treatment endanger the health of hemodialysis patients. Hope therapy focuses on human abilities and capabilities instead of weaknesses using a positive psychology approach. Objectives: This study aimed to evaluate the effect of group hope therapy (GHT) on reducing anxiety and adherence to treatment (ATT) in hemodialysis patients. Methods: This semi-experimental study was conducted with a pre-test and post-test on 40 patients undergoing hemodialysis as consecutive non-probability sampling from among the clients of two hemodialysis centers in Khorram Abad, Iran, in 2017. Primary data of the study was collected using the Spielberger State-Trait Anxiety Inventory (STAI) and End-Stage Renal Disease Adherence Questionnaire (ESRD-AQ) in four stages, including before the intervention, immediately after the intervention, one and three months after the intervention. Hope therapy intervention was implemented in groups of five people for eight sessions (one session per week and each session for 60 minutes) by the researcher and with the supervision and approval of a psychiatrist and a clinical psychologist. The data were analyzed in the SPSS software version 21 at the significance level (α = 0.05). In addition, Cronbach’s alpha test was used to measure the reliability of the questionnaires. Results: There was a significant difference in the mean scores of anxiety and ATT between the two stages “before the intervention" and “immediately after the intervention" (P < 0.05). In addition, there was no significant compliance with the treatment between the two stages “immediately after the intervention" and “three months after the intervention" (P < 0.05), while the average scores of Overt and covert anxiety were significant (P < 0.05). Conclusions: Based on the results, GHT effectively reduces overt and hidden anxiety and increases ATT in hemodialysis patients. Therefore, these results can help plan care for hemodialysis patients. Counseling sessions related to GHT should be offered for consecutive periods in educational and treatment centers by people with experience and training in working with hemodialysis patients.