We have had experience of an 18-month-old boy with a cardiomyopathy who died a few minutes after removal of his cast with a saw, apparently from a malignant cardiac arrhythmia triggered by anxiety. We therefore examined the anxiety reaction to this method of removal of a plaster cast in 20 healthy children; ten were provided with hearing protectors and ten were not. The level of anxiety was assessed by measuring the heart rate, a known physiological indicator of anxiety, before, during and five minutes after removal of the cast. The noise level was also measured. The results showed a mean increase in heart rate during the procedure of 27.9 beats per minute (bpm) (26.9%) in the children with no hearing protectors and 10.4 bpm (11.1%) in children who used hearing protectors (p < 0.001). Five minutes after the procedure the heart rate had returned to the baseline rate in all patients. We recommend that hearing protectors should be used in children undergoing removal of a plaster cast to decrease the anxiety reaction. If possible, clinicians should avoid the use of a saw for this purpose in children with a cardiomyopathy.