Surgical removal of filariae from the jugular vein was performed on 151 dogs with vena cava syndrome. In 8 cases which died without improvement of the systolic regurgitant murmur either during or after surgery, postmortem examination of the thoracic organs was performed. Coiling of filariae around the chordae tendinae of the right ventricle was found in 6 of8 hearts. This paper reports 3 cases. In all 3 coses, worms coiled around the chordae tendineae of the cuspis angularis, These cases suggest that filariae are accidentally trapped by the chordae tendineae and coiling ocurrs due to the regurgitant blood stream from the right atrium to the right ventricle caused by the resultant tricuspid failure. In spite of the small number of parasites, filarial coiling around the chordae tendineae causes severecongestive symptoms and has a poor progrosis.