The objectives of the study were to assess the level of anxiety of patients receiving radiation therapy using State Anxiety Inventory, determine the effectiveness of instrumental music on anxiety among patients of experimental group and find out the association between level of anxiety and selected demographic and clinical variables. Wiedenbach's helping art of clinical nursing theory helped the researcher in the development of the conceptual framework. This quasi experimental study with a pretest- posttest control group design and purposive sampling technique was conducted on 40 patients receiving radiation therapy in a selected hospital at Calicut. A structured questionnaire on demographic and clinical profile and State Anxiety Inventory was used to assess the level of anxiety among the sample. The findings of the study revealed that 80% of subjects from both the experimental and control group were having moderate level of anxiety. There was a significant reduction in the level of anxiety among the experimental group after instrumental music intervention (p=0.001). There was a significant difference in the post test level of anxiety among the experimental group than the control group (p=0.001). The level of anxiety had no significant association with socio demographic variables.