A case of right atrial myxoma is reported in a 6-year-old boy. This type of cardiac tumour is infrequent at this age and its localisation on the right atrium is extremely rare. The clinical diagnosis may be evoked in the presence of a changing cardiac murmur; two-dimensional cardiac ultrasonography is currently the best method for non-invasive assessment. Good surgical results are linked to an early resection, with careful manipulation of the tumour and large removal of the implantation base.