This research intended to determine the effects of the muscle relaxation techniques on anxiety of parents having children with leukaemia who were undergoing chemotherapy at teaching hospitals of Zahedan in 2015.This was a randomized case-control intervention study. The study population consisted of 120 parents of children with leukaemia referred to teaching hospitals in Zahedan and undergoing chemotherapy. These parents were divided into the intervention and control groups, and the intervention group received muscle relaxation using Benson relaxation technique. Data collection tools included the demographic information questionnaire and the questionnaire for assessing apparent and hidden anxiety. Results showed a statistically significant difference between apparent and hidden anxiety in the intervention and control group after the intervention and a significant relationship between apparent anxiety and education level (p ≤ 0.05). the findings of this research can lay the groundwork for providing family-oriented nursing care to give greater support to parents of children with cancer in order to prepare the parents for confronting stresses resulting from their children’s illness.