Objective: This study sought to determine the effects of lavender aromatherapy on pain following needle insertion into a fistula in patients undergoing hemodialysis. Method: This is a randomized controlled clinical trial in which 92 patients undergoing hemodialysis with arteriovenous fistulas were randomly divided into two groups. The experimental-group patients inhaled lavender essence with a concentration of 10% for 5min during 3 hemodialysis sessions, while the control-group patients received aromatherapy free of lavender essence. Results: The mean VAS pain intensity score in the experimental and control groups before the intervention was 3.78±0.24 and 4.16±0.32, respectively (p=0.35). The mean VAS pain intensity score in the experimental and control groups after three aromatherapy sessions was 2.36±0.25 and 3.43±0.31, respectively (p=0.009). Conclusion: Lavender aromatherapy may be an effective technique to reduce pain following needle insertion into a fistula in hemodialysis patients.